Oligomer-diarylpiperazine conjugates

ABSTRACT

The invention relates to (among other things) oligomer-diarylpiperazine conjugates and related compounds. A conjugate of the invention, when administered by any of a number of administration routes, exhibits advantages over previously administered un-conjugated diarylpiperazine compounds.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/864,481, filed 16 Sep. 2011, which is a 35 U.S.C. §371 application ofInternational Application No. PCT/US2009/000475, filed 22 Jan. 2009,designating the United States, which claims the benefit of priorityunder 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No.61/062,330, filed 25 Jan. 2008, both of which are incorporated herein byreference in their entireties.

FIELD OF THE INVENTION

This invention comprises (among other things) chemically modified opioiddiarylpiperazines that possess certain advantages over opioiddiarylpiperazines lacking the chemical modification. The chemicallymodified opioid diarylpiperazines described herein relate to and/or haveapplication(s) in (among others) the fields of drug discovery,pharmacotherapy, physiology, organic chemistry and polymer chemistry.

BACKGROUND OF THE INVENTION

Opioid drugs, such as morphine, have long been used to treat patientssuffering from pain. Opioid drugs exert their analgesic and otherpharmacological effects through interactions with opioid receptors: mu(μ) receptors, kappa (κ) receptors, delta (δ) receptors, and sigma (σ)receptors.

The well-known narcotic opiates, such as morphine and its analogs, areselective for the opiate mu receptor. Mu receptors mediate analgesia,respiratory depression, and inhibition of gastrointestinal transit.Kappa receptors mediate analgesia and sedation. Sigma receptors mediatevarious biological activities.

The existence of the opioid delta receptor is a recent discovery whichfollowed the isolation and characterization of endogenous enkephalinpeptides which are ligands for the delta receptor. Research has producedsignificant information about the delta receptor, but a clearunderstanding of its function has not yet emerged. Delta receptorsmediate analgesia, but do not appear to inhibit intestinal transit inthe manner characteristic of mu receptors.

Pharmacologically, opioid drugs represent a class of agents employed inthe management of pain, and also in combating drug addiction, alcoholaddiction, drug overdose, mental illness, urinary incontinence, cough,lung edema, diarrhea, depression, and cognitive, respiratory, andgastro-intestinal disorders. Unfortunately, the use of opioid drugs isassociated with the potential for abuse. In addition, oraladministration of opioid drugs often results in significant first passmetabolism. Furthermore, administration of opioid drugs results insignificant CNS-mediated effects, such as slowed breathing, which mayresult in death. Thus, a reduction of any one of these or othercharacteristics would enhance their desirability as therapeutic agents.

Recently, a class of potent and selective delta opioid receptor bindingagents, diarylpiperazines (including compound BW373U86), has beendescribed (See U.S. Pat. No. 5,658,908, and Chang, K. J., et al.; J.Pharmacol. Exp. Ther. 267, 852-857 (1993)). However, preliminaryexperiments have suggested that BW373U86 may produce an increase inhyperactivity, including convulsions (Corner, S., et al; J. Pharmacol.Exp. Ther. 267, 888-895 (1993)). Therefore, pharmacotherapy with opioiddiarylpiperazines would be improved if these and/or other side effectsassociated with their use could be decreased or if their pharmacologycould be improved. Thus, there is a large unmet need for developingnovel opioid diarylpiperazine compounds.

The present invention seeks to address these and other needs in the art.

SUMMARY OF THE INVENTION

In one or more embodiments of the invention, a compound is provided, thecompound comprising an opioid diarylpiperazine residue covalentlyattached via a stable or degradable linkage to a water-soluble,non-peptidic oligomer.

Exemplary compounds of the invention include those having the followingstructure:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined at a ringcarbon atom (i.e., at a ring carbon atom of Ar);Y is selected from the group consisting of:hydrogen; halogen; C₁-C₆ alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆alkoxy; C₃-C₆ cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are thesame as above; and CONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;Z is selected from the group consisting of hydroxyl, and acyl estersthereof whose acyl moiety is selected from the group consisting ofCH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO;hydroxymethyl, and acyl esters thereof whose acyl moiety is selectedfrom the group consisting of CH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO; andamino, formamidyl and benzenesulfonamidyl;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁶ is selected from the group consisting of hydrogen; C₁-C₆ alkyl; C₃-C₆cycloalkyl; allyl; 2-buten-1-yl; 2-methyl-2-propen-1-yl;2-chloro-2-propen-1-yl; alkoxyalkyl having C₁-C₄ alkoxy and C₁-C₄ alkylmoieties; C₂-C₄ cyanoalkyl; C₂-C₄ hydroxyalkyl; aminocarbonylalkylhaving a C₁-C₄ alkyl moiety; alkylaryl having C₁-C₄ alkylene and C₆-C₁₄aryl moieties; and R¹²COR¹³, where R¹² is C₁-C₄ alkylene, and R¹³ isC₁-C₄ alkyl or C₁-C₄ alkoxy;R⁷ is hydrogen or fluorine, subject to the proviso that: R¹, R² and R⁷may be fluorine only when Z is —OH;X is a spacer moiety, and is covalently attached to an atom; andPOLY is a water-soluble, non-peptidic oligomer.

Further exemplary compounds include those having the followingstructure:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined at a ringcarbon atom (i.e., at a ring carbon atom of Ar);Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl;C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆ cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove;sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; andCONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁶ is selected from the group consisting of hydrogen; C₁-C₆ alkyl; C₃-C₆cycloalkyl; allyl; 2-buten-1-yl; 2-methyl-2-propen-1-yl;2-chloro-2-propen-1-yl; alkoxyalkyl having C₁-C₄ alkoxy and C₁-C₄ alkylmoieties; C₂-C₄ cyanoalkyl; C₂-C₄ hydroxyalkyl;aminocarbonylalkyl having a C₁-C₄ alkyl moiety; alkylaryl having C₁-C₄alkylene and C₆-C₁₄ aryl moieties; and R¹²COR¹³, where R¹² is C₁-C₄alkylene, and R¹³ is C₁-C₄ alkyl or C₁-C₄ alkoxy;R⁷ is hydrogen or fluorine;X is a spacer moiety; andPOLY is a water-soluble, non-peptidic oligomer.

Exemplary compounds include those having the following structure:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined at a ringcarbon atom (i.e., at a ring carbon atom of Ar);Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove;sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; andCONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;Z is selected from the group consisting of hydroxyl, and acyl estersthereof whose acyl moiety is selected from the group consisting ofCH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO;hydroxymethyl, and acyl esters thereof whose acyl moiety is selectedfrom the group consisting of CH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO; andamino, formamidyl and benzenesulfonamidyl;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁷ is hydrogen or fluorine, subject to the proviso that: R¹, R² and R⁷may be fluorine only when Z is —OH;X is a spacer moiety; andPOLY is a water-soluble, non-peptidic oligomer.

The “opioid diarylpiperazine residue” is a compound having a structureof an opioid diarylpiperazine compound that is altered by the presenceof one or more bonds, which bonds serve to attach (either directly orindirectly) one or more water-soluble, non-peptidic oligomers.

In this regard, any diarylpiperazine compound having opioid deltareceptor binding activity can be used as an opioid diarylpiperazinemoiety. Exemplary opioid diarylpiperazine moieties have a structureencompassed by Formula I:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined to thecompound at a ring carbon atom of the Ar ring;Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove;sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; andCONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;Z is selected from the group consisting of hydroxyl, and acyl estersthereof whose acyl moiety is selected from the group consisting ofCH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO;hydroxymethyl, and acyl esters thereof whose acyl moiety is selectedfrom the group consisting of CH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO; andamino, formamidyl and benzenesulfonamidyl;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁶ is selected from the group consisting of hydrogen; C₁-C₆ alkyl; C₃-C₆cycloalkyl; allyl; 2-buten-1-yl; 2-methyl-2-propen-1-yl;2-chloro-2-propen-1-yl; alkoxyalkyl having C₁-C₄ alkoxy and C₁-C₄ alkylmoieties; C₂-C₄ cyanoalkyl; C₂-C₄ hydroxyalkyl;aminocarbonylalkyl having a C₁-C₄ alkyl moiety; alkylaryl having C₁-C₄alkylene and C₆-C₁₄ aryl moieties; and R¹²COR¹³, where R¹² is C₁-C₄alkylene, and R¹³ is C₁-C₄ alkyl or C₁-C₄ alkoxy; andR⁷ is hydrogen or fluorine, subject to the proviso that: R¹, R² and R⁷may be fluorine only when Z is —OH.

In one or more embodiments of the invention, a composition is provided,the composition comprising a compound comprising an opioiddiarylpiperazine residue covalently attached via a stable or degradablelinkage to a water-soluble, non-peptidic oligomer, and optionally, apharmaceutically acceptable excipient.

In one or more embodiments of the invention, a dosage form is provided,the dosage form comprising a compound comprising an opioiddiarylpiperazine residue covalently attached via a stable or degradablelinkage to a water-soluble, non-peptidic oligomer, wherein the compoundis present in a dosage form.

In one or more embodiments of the invention, a method is provided, themethod comprising covalently attaching a water-soluble, non-peptidicoligomer to an opioid diarylpiperazine moiety.

In one or more embodiments of the invention, a method is provided, themethod comprising administering a compound comprising an opioiddiarylpiperazine residue covalently attached via a stable or degradablelinkage to a water-soluble, non-peptidic oligomer.

These and other objects, aspects, embodiments and features of theinvention will become more fully apparent to one of ordinary skill inthe art when read in conjunction with the following detaileddescription.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 and 2 show opioid delta receptor binding assay for BW373U86 andBW373U86-PEG conjugates to CHO-delta clone #16.

DETAILED DESCRIPTION OF THE INVENTION

As used in this specification, the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions describedbelow.

“Water soluble, non-peptidic oligomer” indicates an oligomer that is atleast 35% (by weight) soluble, preferably greater than 70% (by weight),and more preferably greater than 95% (by weight) soluble, in water atroom temperature. Typically, an unfiltered aqueous preparation of a“water-soluble” oligomer transmits at least 75%, more preferably atleast 95%, of the amount of light transmitted by the same solution afterfiltering. It is most preferred, however, that the water-solubleoligomer is at least 95% (by weight) soluble in water or completelysoluble in water. With respect to being “non-peptidic,” an oligomer isnon-peptidic when it has less than 35% (by weight) of amino acidresidues.

The terms “monomer,” “monomeric subunit” and “monomeric unit” are usedinterchangeably herein and refer to one of the basic structural units ofa polymer or oligomer. In the case of a homo-oligomer, a singlerepeating structural unit forms the oligomer. In the case of aco-oligomer, two or more structural units are repeated—either in apattern or randomly—to form the oligomer. Preferred oligomers used inconnection with present the invention are homo-oligomers. Thewater-soluble, non-peptidic oligomer typically comprises one or moremonomers serially attached to form a chain of monomers. The oligomer canbe formed from a single monomer type (i.e., is homo-oligomeric) or twoor three monomer types (i.e., is co-oligomeric).

An “oligomer” is a molecule possessing from about 1 to about 30monomers. Specific oligomers for use in the invention include thosehaving a variety of geometries such as linear, branched, or forked, tobe described in greater detail below.

“PEG” or “polyethylene glycol,” as used herein, is meant to encompassany water-soluble poly(ethylene oxide). Unless otherwise indicated, a“PEG oligomer” or an oligoethylene glycol is one in which substantiallyall (preferably all) monomeric subunits are ethylene oxide subunits,though, the oligomer may contain distinct end capping moieties orfunctional groups, e.g., for conjugation. PEG oligomers for use in thepresent invention will comprise one of the two following structures:“—(CH₂CH₂O)_(n)—” or “—(CH₂CH₂O)_(n-1) CH₂CH₂—,” depending upon whetheror not the terminal oxygen(s) has been displaced, e.g., during asynthetic transformation. As stated above, for the PEG oligomers, thevariable (n) ranges from about 1 to 30, and the terminal groups andarchitecture of the overall PEG can vary. When PEG further comprises afunctional group, A, for linking to, e.g., a small molecule drug, thefunctional group when covalently attached to a PEG oligomer does notresult in formation of (i) an oxygen-oxygen bond (—O—O—, a peroxidelinkage), or (ii) a nitrogen-oxygen bond (N—O, O—N).

The terms “end-capped” or “terminally capped” are interchangeably usedherein to refer to a terminal or endpoint of a polymer having anend-capping moiety. Typically, although not necessarily, the end-cappingmoiety comprises a hydroxy or C₁₋₂₀ alkoxy group. Thus, examples ofend-capping moieties include alkoxy (e.g., methoxy, ethoxy andbenzyloxy), as well as aryl, heteroaryl, cyclo, heterocyclo, and thelike. In addition, saturated, unsaturated, substituted and unsubstitutedforms of each of the foregoing are envisioned. Moreover, the end-cappinggroup can also be a silane. The end-capping group can alsoadvantageously comprise a detectable label. When the polymer has anend-capping group comprising a detectable label, the amount or locationof the polymer and/or the moiety (e.g., active agent) of interest towhich the polymer is coupled, can be determined by using a suitabledetector. Such labels include, without limitation, fluorescers,chemiluminescers, moieties used in enzyme labeling, colorimetricmoieties (e.g., dyes), metal ions, radioactive moieties, and the like.Suitable detectors include photometers, films, spectrometers, and thelike. In addition, the end-capping group may contain a targeting moiety.

The term “targeting moiety” is used herein to refer to a molecularstructure that helps the conjugates of the invention to localize to atargeting area, e.g., help enter a cell, or bind a receptor. Preferably,the targeting moiety comprises of vitamin, antibody, antigen, receptor,DNA, RNA, sialyl Lewis X antigen, hyaluronic acid, sugars, cell specificlectins, steroid or steroid derivative, RGD peptide, ligand for a cellsurface receptor, serum component, or combinatorial molecule directedagainst various intra- or extracellular receptors. The targeting moietymay also comprise a lipid or a phospholipid. Exemplary phospholipidsinclude, without limitation, phosphatidylcholines, phospatidylserine,phospatidylinositol, phospatidylglycerol, and phospatidylethanolamine.These lipids may be in the form of micelles or liposomes and the like.The targeting moiety may further comprise a detectable label oralternately a detectable label may serve as a targeting moiety. When theconjugate has a targeting group comprising a detectable label, theamount and/or distribution/location of the polymer and/or the moiety(e.g., active agent) to which the polymer is coupled can be determinedby using a suitable detector. Such labels include, without limitation,fluorescers, chemiluminescers, moieties used in enzyme labeling,colorimetric (e.g., dyes), metal ions, radioactive moieties, goldparticles, quantum dots, and the like.

“Branched,” in reference to the geometry or overall structure of anoligomer, refers to an oligomer having two or more polymers “arms”extending from a branch point.

“Forked,” in reference to the geometry or overall structure of anoligomer, refers to an oligomer having two or more functional groups(typically through one or more atoms) extending from a branch point.

A “branch point” refers to a bifurcation point comprising one or moreatoms at which an oligomer branches or forks from a linear structureinto one or more additional arms.

The term “reactive” or “activated” refers to a functional group thatreacts readily or at a practical rate under conventional conditions oforganic synthesis. This is in contrast to those groups that either donot react or require strong catalysts or impractical reaction conditionsin order to react (i.e., a “nonreactive” or “inert” group).

“Not readily reactive,” with reference to a functional group present ona molecule in a reaction mixture, indicates that the group remainslargely intact under conditions that are effective to produce a desiredreaction in the reaction mixture.

A “protecting group” is a moiety that prevents or blocks reaction of aparticular chemically reactive functional group in a molecule undercertain reaction conditions. The protecting group may vary dependingupon the type of chemically reactive group being protected as well asthe reaction conditions to be employed and the presence of additionalreactive or protecting groups in the molecule. Functional groups whichmay be protected include, by way of example, carboxylic acid groups,amino groups, hydroxyl groups, thiol groups, carbonyl groups and thelike. Representative protecting groups for carboxylic acids includeesters (such as a p-methoxybenzyl ester), amides and hydrazides; foramino groups, carbamates (such as tert-butoxycarbonyl) and amides; forhydroxyl groups, ethers and esters; for thiol groups, thioethers andthioesters; for carbonyl groups, acetals and ketals; and the like. Suchprotecting groups are well-known to those skilled in the art and aredescribed, for example, in T. W. Greene and G. M. Wuts, ProtectingGroups in Organic Synthesis, Third Edition, Wiley, New York, 1999, andreferences cited therein.

A functional group in “protected form” refers to a functional groupbearing a protecting group. As used herein, the term “functional group”or any synonym thereof encompasses protected forms thereof.

A “physiologically cleavable” or “hydrolyzable” or “degradable” bond isa relatively labile bond that reacts with water (i.e., is hydrolyzed)under physiological conditions. The tendency of a bond to hydrolyze inwater may depend not only on the general type of linkage connecting twocentral atoms but also on the substituents attached to these centralatoms. Appropriate hydrolytically unstable or weak linkages include butare not limited to carboxylate ester, phosphate ester, anhydrides,acetals, ketals, acyloxyalkyl ether, imines, orthoesters, peptides,oligonucleotides, thioesters, and carbonates.

An “enzymatically degradable linkage” means a linkage that is subject todegradation by one or more enzymes.

A “stable” linkage or bond refers to a chemical bond that issubstantially stable in water, that is to say, does not undergohydrolysis under physiological conditions to any appreciable extent overan extended period of time. Examples of hydrolytically stable linkagesinclude but are not limited to the following: carbon-carbon bonds (e.g.,in aliphatic chains), ethers, amides, urethanes, amines, and the like.Generally, a stable linkage is one that exhibits a rate of hydrolysis ofless than about 1-2% per day under physiological conditions. Hydrolysisrates of representative chemical bonds can be found in most standardchemistry textbooks.

“Substantially” or “essentially” means nearly totally or completely, forinstance, 95% or greater, more preferably 97% or greater, still morepreferably 98% or greater, even more preferably 99% or greater, yetstill more preferably 99.9% or greater, with 99.99% or greater beingmost preferred of some given quantity.

“Monodisperse” refers to an oligomer composition wherein substantiallyall of the oligomers in the composition have a well-defined, singlemolecular weight and defined number of monomers, as determined bychromatography or mass spectrometry. Monodisperse oligomer compositionsare in one sense pure, that is, substantially having a single anddefinable number (as a whole number) of monomers rather than a largedistribution. A monodisperse oligomer composition possesses a MW/Mnvalue of 1.0005 or less, and more preferably, a MW/Mn value of 1.0000.By extension, a composition comprised of monodisperse conjugates meansthat substantially all oligomers of all conjugates in the compositionhave a single and definable number (as a whole number) of monomersrather than a large distribution and would possess a MW/Mn value of1.0005, and more preferably, a MW/Mn value of 1.0000 if the oligomerwere not attached to the therapeutic moiety. A composition comprised ofmonodisperse conjugates may, however, include one or more non-conjugatesubstances such as solvents, reagents, excipients, and so forth.

“Bimodal,” in reference to an oligomer composition, refers to anoligomer composition wherein substantially all oligomers in thecomposition have one of two definable and different numbers (as wholenumbers) of monomers rather than a large distribution, and whosedistribution of molecular weights, when plotted as a number fractionversus molecular weight, appears as two separate identifiable peaks.Preferably, for a bimodal oligomer composition as described herein, eachpeak is generally symmetric about its mean, although the size of the twopeaks may differ. Ideally, the polydispersity index of each peak in thebimodal distribution, Mw/Mn, is 1.01 or less, more preferably 1.001 orless, and even more preferably 1.0005 or less, and most preferably aMW/Mn value of 1.0000. By extension, a composition comprised of bimodalconjugates means that substantially all oligomers of all conjugates inthe composition have one of two definable and different numbers (aswhole numbers) of monomers rather than a large distribution and wouldpossess a MW/Mn value of 1.01 or less, more preferably 1.001 or less andeven more preferably 1.0005 or less, and most preferably a MW/Mn valueof 1.0000 if the oligomer were not attached to the therapeutic moiety. Acomposition comprised of bimodal conjugates may, however, include one ormore non-conjugate substances such as solvents, reagents, excipients,and so forth.

An “opioid diarylpiperazine” is broadly used herein to refer to anorganic, inorganic, or organometallic compound having a molecular weightof less than about 1000 Daltons and having some degree of activity asantihypertensive therapeutic. Antihypertensive activity of a compoundmay be measured by assays known in the art and also as described hereinlater.

A “biological membrane” is any membrane made of cells or tissues thatserves as a barrier to at least some foreign entities or otherwiseundesirable materials. As used herein a “biological membrane” includesthose membranes that are associated with physiological protectivebarriers including, for example: the blood-brain barrier (BBB); theblood-cerebrospinal fluid barrier; the blood-placental barrier; theblood-milk barrier; the blood-testes barrier; and mucosal barriersincluding the vaginal mucosa, urethral mucosa, anal mucosa, buccalmucosa, sublingual mucosa, and rectal mucosa. Unless the context clearlydictates otherwise, the term “biological membrane” does not includethose membranes associated with the middle gastro-intestinal tract(e.g., stomach and small intestines).

A “biological membrane crossing rate,” provides a measure of acompound's ability to cross a biological membrane, such as theblood-brain barrier (“BBB”). A variety of methods may be used to assesstransport of a molecule across any given biological membrane. Methods toassess the biological membrane crossing rate associated with any givenbiological barrier (e.g., the blood-cerebrospinal fluid barrier, theblood-placental barrier, the blood-milk barrier, the intestinal barrier,and so forth), are known, described herein and/or in the relevantliterature, and/or may be determined by one of ordinary skill in theart.

A “reduced rate of metabolism” refers to a measurable reduction in therate of metabolism of a water-soluble oligomer-small molecule drugconjugate as compared to the rate of metabolism of the small moleculedrug not attached to the water-soluble oligomer (i.e., the smallmolecule drug itself) or a reference standard material. In the specialcase of “reduced first pass rate of metabolism,” the same “reduced rateof metabolism” is required except that the small molecule drug (orreference standard material) and the corresponding conjugate areadministered orally. Orally administered drugs are absorbed from thegastro-intestinal tract into the portal circulation and may pass throughthe liver prior to reaching the systemic circulation. Because the liveris the primary site of drug metabolism or biotransformation, asubstantial amount of drug may be metabolized before it ever reaches thesystemic circulation. The degree of first pass metabolism, and thus, anyreduction thereof, may be measured by a number of different approaches.For instance, animal blood samples may be collected at timed intervalsand the plasma or serum analyzed by liquid chromatography/massspectrometry for metabolite levels. Other techniques for measuring a“reduced rate of metabolism” associated with the first pass metabolismand other metabolic processes are known, described herein and/or in therelevant literature, and/or may be determined by one of ordinary skillin the art. Preferably, a conjugate of the invention may provide areduced rate of metabolism reduction satisfying at least one of thefollowing values: at least about 30%; at least about 40%; at least about50%; at least about 60%; at least about 70%; at least about 80%; and atleast about 90%. A compound (such as a small molecule drug or conjugatethereof) that is “orally bioavailable” is one that preferably possessesa bioavailability when administered orally of greater than 25%, andpreferably greater than 70%, where a compound's bioavai lability is thefraction of administered drug that reaches the systemic circulation inunmetabolized form.

“Alkyl” refers to a hydrocarbon chain, ranging from about 1 to 20 atomsin length. Such hydrocarbon chains are preferably but not necessarilysaturated and may be branched or straight chain. Exemplary alkyl groupsinclude methyl, ethyl, propyl, butyl, pentyl, 2-methylbutyl,2-ethylpropyl, 3-methylpentyl, and the like. As used herein, “alkyl”includes cycloalkyl when three or more carbon atoms are referenced. An“alkenyl” group is an alkyl of 2 to 20 carbon atoms with at least onecarbon-carbon double bond.

The terms “substituted alkyl” or “substituted C_(q), alkyl” where q andr are integers identifying the range of carbon atoms contained in thealkyl group, denotes the above alkyl groups that are substituted by one,two or three halo (e.g., F, Cl, Br, I), trifluoromethyl, hydroxy, C₁₋₇alkyl (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, t-butyl, and soforth), C₁₋₇ alkoxy, C₁₋₇ acyloxy, C₃₋₇ heterocyclic, amino, phenoxy,nitro, carboxy, acyl, cyano. The substituted alkyl groups may besubstituted once, twice or three times with the same or with differentsubstituents.

“Lower alkyl” refers to an alkyl group containing from 1 to 6 carbonatoms, and may be straight chain or branched, as exemplified by methyl,ethyl, n-butyl, i-butyl, and t-butyl. “Lower alkenyl” refers to a loweralkyl group of 2 to 6 carbon atoms having at least one carbon-carbondouble bond.

“Non-interfering substituents” are those groups that, when present in amolecule, are typically non-reactive with other functional groupscontained within the molecule.

“Alkoxy” refers to an —O—R group, wherein R is alkyl or substitutedalkyl, preferably C₁-C₂₀ alkyl (e.g., methoxy, ethoxy, propyloxy, etc.),preferably C₁-C₇.

“Pharmaceutically acceptable excipient” or “pharmaceutically acceptablecarrier” refers to component that may be included in the compositions ofthe invention causes no significant adverse toxicological effects to apatient.

The term “aryl” means an aromatic group having up to 14 carbon atoms.Aryl groups include phenyl, naphthyl, biphenyl, phenanthrenyl,naphthalenyl, and the like. “Substituted phenyl” and “substituted aryl”denote a phenyl group and aryl group, respectively, substituted withone, two, three, four or five (e.g. 1-2, 1-3 or 1-4 substituents) chosenfrom halo (F, Cl, Br, I), hydroxy, cyano, nitro, alkyl (e.g., C₁₋₆alkyl), alkoxy (e.g. C₁₋₆ alkoxy), benzyloxy, carboxy, aryl, and soforth.

Chemical moieties are defined and referred to throughout primarily asunivalent chemical moieties (e.g., alkyl, aryl, etc.). Nevertheless,such terms are also used to convey corresponding multivalent moietiesunder the appropriate structural circumstances clear to those skilled inthe art. For example, while an “alkyl” moiety generally refers to amonovalent radical (e.g., CH₃—CH₂—), in certain circumstances a bivalentlinking moiety can be “alkyl,” in which case those skilled in the artwill understand the alkyl to be a divalent radical (e.g., —CH₂—CH₂—),which is equivalent to the term “alkylene.” (Similarly, in circumstancesin which a divalent moiety is required and is stated as being “aryl,”those skilled in the art will understand that the term “aryl” refers tothe corresponding multivalent moiety, arylene). All atoms are understoodto have their normal number of valences for bond formation (i.e., 1 forH, 4 for carbon, 3 for N, 2 for O, and 2, 4, or 6 for S, depending onthe oxidation state of the S).

“Pharmacologically effective amount,” “physiologically effectiveamount,” and “therapeutically effective amount” are used interchangeablyherein to mean the amount of a water-soluble oligomer-small moleculedrug conjugate present in a composition that is needed to provide adesired level of active agent and/or conjugate in the bloodstream or inthe target tissue. The precise amount may depend upon numerous factors,e.g., the particular active agent, the components and physicalcharacteristics of the composition, intended patient population, patientconsiderations, and may readily be determined by one skilled in the art,based upon the information provided herein and available in the relevantliterature.

A “difunctional” oligomer is an oligomer having two functional groupscontained therein, typically at its termini. When the functional groupsare the same, the oligomer is said to be homodifunctional. When thefunctional groups are different, the oligomer is said to beheterodifunctional.

A basic reactant or an acidic reactant described herein include neutral,charged, and any corresponding salt forms thereof.

The term “patient,” refers to a living organism suffering from or proneto a condition that can be prevented or treated by administration of aconjugate as described herein, and includes both humans and animals.

“Optional” or “optionally” means that the subsequently describedcircumstance may but need not necessarily occur, so that the descriptionincludes instances where the circumstance occurs and instances where itdoes not.

“Nil” refers to the absence of a substituent group. Thus, when asubstituent is nil, the substituent may be represented in the structureas a chemical bond or hydrogen in the resulting structure.

As indicated above, the present invention is directed to (among otherthings) a compound comprising an opioid diarylpiperazine residuecovalently attached via a stable or degradable linkage to awater-soluble, non-peptidic oligomer.

The “opioid diarylpiperazine residue” is a compound having a structureof an opioid diarylpiperazine compound that is altered by the presenceof one or more bonds, which bonds serve to attach (either directly orindirectly) one or more water-soluble, non-peptidic oligomers. Exemplaryopioid diarylpiperazines have a structure encompassed by at least one ofthe structures defined herein as Formula I:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined to thecompound at a ring carbon atom of the Ar ring;Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are thesame as above; and CONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;Z is selected from the group consisting of hydroxyl, and acyl estersthereof whose acyl moiety is selected from the group consisting ofCH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO;hydroxymethyl, and acyl esters thereof whose acyl moiety is selectedfrom the group consisting of CH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO; andamino, formamidyl and benzenesulfonamidyl;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁶ is selected from the group consisting of hydrogen; C₁-C₆ alkyl; C₃-C₆cycloalkyl; allyl; 2-buten-1-yl; 2-methyl-2-propen-1-yl;2-chloro-2-propen-1-yl; alkoxyalkyl having C₁-C₄ alkoxy and C₁-C₄ alkylmoieties; C₂-C₄ cyanoalkyl; C₂-C₄ hydroxyalkyl;aminocarbonylalkyl having a C₁-C₄ alkyl moiety; alkylaryl having C₁-C₄alkylene and C₆-C₁₄ aryl moieties; and R¹²COR¹³, where R¹² is C₁-C₄alkylene, and R¹³ is C₁-C₄ alkyl or C₁-C₄ alkoxy; andR⁷ is hydrogen or fluorine, subject to the proviso that: R′, R² and R⁷may be fluorine only when Z is —OH.

In one or more embodiments of the invention, a compound is provided, thecompound comprising an opioid diarylpiperazine residue covalentlyattached via a stable or degradable linkage to a water-soluble,non-peptidic oligomer, wherein the opioid diarylpiperazine has astructure encompassed by the following formula:

4-((S)-((2S,5R)-4-allyl-2,5-dimethylpiperazin-1-yl)(3-hydroxyphenyl)methyl)-N,N-diethylbenzamide

In one or more embodiments of the invention, a compound is provided, thecompound comprising an opioid diarylpiperazine residue covalentlyattached via a stable or degradable linkage to a water-soluble,non-peptidic oligomer, wherein the opioid diarylpiperazine has astructure encompassed by the following formula:

4-((R)-((2S,5R)-4-allyl-2,5-dimethylpiperazin-1-yl)(3-hydroxyphenyl)methyl)-N,N-diethylbenzamide.

In one or more embodiments of the invention, a compound is provided, thecompound comprising an opioid diarylpiperazine residue covalentlyattached via a stable or degradable linkage to a water-soluble,non-peptidic oligomer, wherein the opioid diarylpiperazine has astructure encompassed by the following formula:

4-((4-benzylpiperazin-1-yl)(3-hydroxyphenyl)methyl)-N,N-diethylbenzamide,and enantiomers and diastereomers thereof.

In one or more embodiments of the invention, a compound is provided, thecompound comprising an opioid diarylpiperazine residue covalentlyattached via a stable or degradable linkage to a water-soluble,non-peptidic oligomer, wherein the opioid diarylpiperazine has astructure encompassed by the following formula:

4-((S)-((2S,5R)-2,5-dimethylpiperazin-1-yl)(3-hydroxyphenyl)methyl)-N,N-diethylbenzamide.

In one or more embodiments of the invention, a compound is provided, thecompound comprising an opioid diarylpiperazine residue covalentlyattached via a stable or degradable linkage to a water-soluble,non-peptidic oligomer, wherein the opioid diarylpiperazine has astructure encompassed by the following formula:

4-((R)-((2S,5R)-2,5-dimethylpiperazin-1-yl)(3-hydroxyphenyl)methyl)-N,N-diethylbenzamide.

In some instances, opioid diarylpiperazines can be obtained fromcommercial sources. In addition, opioid diarylpiperazines can beobtained through chemical synthesis. Examples of opioiddiarylpiperazines as well as synthetic approaches for preparing opioiddiarylpiperazines are described in the literature and in, for example,U.S. Pat. No. 5,658,908, and Chang, K. J., et al; J. Pharmacol. Exp.Ther. 267, 852-857 (1993). Each of these (and other) opioiddiarylpiperazines can be covalently attached (either directly or throughone or more atoms) to a water-soluble, non-peptidic oligomer.

Exemplary compounds of the invention include those having the followingstructure:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined at a ringcarbon atom (i.e., at a ring carbon atom of Ar);Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are thesame as above; and CONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;Z is selected from the group consisting of hydroxyl, and acyl estersthereof whose acyl moiety is selected from the group consisting ofCH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO;hydroxymethyl, and acyl esters thereof whose acyl moiety is selectedfrom the group consisting of CH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO; andamino, formamidyl and benzenesulfonamidyl;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁶ is selected from the group consisting of hydrogen; C₁-C₆ alkyl; C₃-C₆cycloalkyl; allyl; 2-buten-1-yl; 2-methyl-2-propen-1-yl;2-chloro-2-propen-1-yl; alkoxyalkyl having C₁-C₄ alkoxy and C₁-C₄ alkylmoieties; C₂-C₄ cyanoalkyl; C₂-C₄ hydroxyalkyl;aminocarbonylalkyl having a C₁-C₄ alkyl moiety; alkylaryl having C₁-C₄alkylene and C₆-C₁₄ aryl moieties; and R¹²COR¹³, where R¹² is C₁-C₄alkylene, and R¹³ is C₁-C₄ alkyl or C₁-C₄ alkoxy;R⁷ is hydrogen or fluorine, subject to the proviso that: R¹, R² and R⁷may be fluorine only when Z is —OH;X is a spacer moiety and is covalently attached to an atom; andPOLY is a water-soluble, non-peptidic oligomer.

Further exemplary compounds of the invention include those having thefollowing structure:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined at a ringcarbon atom (i.e., at a ring carbon atom of Ar);Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove;sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; andCONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁶ is selected from the group consisting of hydrogen; C₁-C₆ alkyl; C₃-C₆cycloalkyl; allyl; 2-buten-1-yl; 2-methyl-2-propen-1-yl;2-chloro-2-propen-1-yl; alkoxyalkyl having C₁-C₄ alkoxy and C₁-C₄ alkylmoieties; C₂-C₄ cyanoalkyl; C₂-C₄ hydroxyalkyl;aminocarbonylalkyl having a C₁-C₄ alkyl moiety; alkylaryl havingalkylene and C₆-C₁₄ aryl moieties; and R¹²COR¹³, where R¹² is C₁-C₄alkylene, and R¹³ is C₁-C₄ alkyl or C₁-C₄ alkoxy;R⁷ is hydrogen or fluorine;X is a spacer moiety; andPOLY is a water-soluble, non-peptidic oligomer.

Exemplary compounds of the invention include those having the followingstructure:

wherein:Ar is a 5- or 6-member aromatic ring selected from the group consistingof thiophenyl, thiazolyl, furanyl, pyrrolyl, phenyl, and pyridyl, havingon a first ring carbon atom thereof a substituent Y and on a second ringcarbon atom thereof a substituent R₁, wherein Ar is joined at a ringcarbon atom (i.e., at a ring carbon atom of Ar);Y is selected from the group consisting of hydrogen; halogen; C₁-C₆alkyl; C₁-C₆ haloalkyl; C₃-C₆ cycloalkyl; C₁-C₆ alkoxy; C₃-C₆cycloalkoxy;sulfides of the formula SR⁸ where R⁸ is C₁-C₆ alkyl, C₃-C₆ cycloalkyl,or phenyl; sulfoxides of the formula SOR⁸ where R⁸ is the same as above;sulfones of the formula SO₂R⁸ where R⁸ is the same as above;nitrile; C₁-C₆ acyl; alkoxycarbonylamino(carbamoyl) of the formulaNHCO₂R⁸ where R⁸ is the same as above; carboxylic acid, or an alkylester; aminomethyl of the formula CH₂NR⁹R¹⁰ where R⁹ and R¹⁰ may be thesame or different, and may be hydrogen, C₁-C₆ alkyl, C₂-C₆ hydroxyalkyl,C₂-C₆ methoxyalkyl, C₃-C₆ cycloalkyl, or phenyl, or R⁹ and R¹⁰ togethermay form a ring selected from the group consisting of pyrrolidinyl,piperidinyl, and 4-methyl-piperazinyl;carboxamides of the formula CONR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove;sulfonamides of the formula SO₂NR⁹R¹⁰ where R⁹ and R¹⁰ are the same asabove; andCONR⁹AB, where:A is a divalent ligand having an alkyl or polyether moiety of 6-12atoms, with the proviso that there are at least two carbon atoms betweenan oxygen atom and the NR⁹ group and at least two carbon atoms betweentwo oxygen atoms when present; andB is a dimer-forming moiety which is joined to a first valence bond ofthe divalent ligand A, and which is symmetric about the divalent ligandA to the compound moiety joined to the other valence bond of thedivalent ligand A;Z is selected from the group consisting of hydroxyl, and acyl estersthereof whose acyl moiety is selected from the group consisting ofCH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO;hydroxymethyl, and acyl esters thereof whose acyl moiety is selectedfrom the group consisting of CH₃CO, C₆H₅CO, (CH₃)₂NCO, and Me₃CCO; andamino, formamidyl and benzenesulfonamidyl;G is nitrogen;R¹ is hydrogen, halogen, or C₁-C₄;R² is hydrogen, halogen, or C₁-C₄;R³, R⁴ and R⁵ may be the same or different, and are independentlyselected from hydrogen and methyl, and wherein at least one of R³, R⁴ orR⁵ is not hydrogen, subject to the proviso that the total number ofmethyl groups does not exceed two;R⁷ is hydrogen or fluorine, subject to the proviso that: R¹, R² and R⁷may be fluorine only when Z is —OH;X is a spacer moiety; andPOLY is a water-soluble, non-peptidic oligomer.

Use of discrete oligomers (e.g., from a monodisperse or bimodalcomposition of oligomers, in contrast to relatively impure compositions)to form oligomer-containing compounds may advantageously alter certainproperties associated with the corresponding small molecule drug. Forinstance, a compound of the invention, when administered by any of anumber of suitable administration routes, such as parenteral, oral,transdermal, buccal, pulmonary, or nasal, exhibits reduced penetrationacross the blood-brain barrier. It is preferred that the compounds ofthe invention exhibit slowed, minimal or effectively no crossing of theblood-brain barrier, while still crossing the gastro-intestinal (GI)walls and into the systemic circulation if oral delivery is intended.Moreover, the compounds of the invention maintain a degree ofbioactivity as well as bioavailability in comparison to the bioactivityand bioavailability of the compound free of all oligomers.

With respect to the blood-brain barrier (“BBB”), this barrier restrictsthe transport of drugs from the blood to the brain. This barrierconsists of a continuous layer of unique endothelial cells joined bytight junctions. The cerebral capillaries, which comprise more than 95%of the total surface area of the BBB, represent the principal route forthe entry of most solutes and drugs into the central nervous system.

For compounds whose degree of blood-brain barrier crossing ability isnot readily known, such ability may be determined using a suitableanimal model such as an in situ rat brain perfusion (“RBP”) model asdescribed herein. Briefly, the RBP technique involves cannulation of thecarotid artery followed by perfusion with a compound solution undercontrolled conditions, followed by a wash out phase to remove compoundremaining in the vascular space. (Such analyses may be conducted, forexample, by contract research organizations such as Absorption Systems,Exton, Pa.). In one example of the RBP model, a cannula is placed in theleft carotid artery and the side branches are tied off. A physiologicbuffer containing the analyte (typically but not necessarily at a 5micromolar concentration level) is perfused at a flow rate of about 10mL/minute in a single pass perfusion experiment. After 30 seconds, theperfusion is stopped and the brain vascular contents are washed out withcompound-free buffer for an additional 30 seconds. The brain tissue isthen removed and analyzed for compound concentrations via liquidchromatograph with tandem mass spectrometry detection (LC/MS/MS).Alternatively, blood-brain barrier permeability can be estimated basedupon a calculation of the compound's molecular polar surface area(“PSA”), which is defined as the sum of surface contributions of polaratoms (usually oxygens, nitrogens and attached hydrogens) in a molecule.The PSA has been shown to correlate with compound transport propertiessuch as blood-brain barrier transport. Methods for determining acompound's PSA can be found, e.g., in, Ertl, P., et al., J. Med. Chem.2000, 43, 3714-3717; and Kelder, J., et al., Pharm. Res. 1999, 16,1514-1519.

With respect to the blood-brain barrier, the water-soluble, non-peptidicoligomer-small molecule drug conjugate exhibits a blood-brain barriercrossing rate that is reduced as compared to the crossing rate of thesmall molecule drug not attached to the water-soluble, non-peptidicoligomer. Exemplary reductions in blood-brain barrier crossing rates forthe compounds described herein include reductions of: at least about 5%;at least about 10%; at least about 25%; at least about 30%; at leastabout 40%; at least about 50%; at least about 60%; at least about 70%;at least about 80%; or at least about 90%, when compared to theblood-brain barrier crossing rate of the small molecule drug notattached to the water-soluble oligomer. A preferred reduction in theblood-brain barrier crossing rate for a conjugate of the invention is atleast about 20%.

Assays for determining whether a given compound (regardless of whetherthe compound includes a water-soluble, non-peptidic oligomer or not) canact as an opioid diarylpiperazine are known and/or may be prepared byone of ordinary skill in the art and are further described infra.

Each of these (and other) diarylpiperazine moieties can be covalentlyattached (either directly or through one or more atoms) to awater-soluble, non-peptidic oligomer.

Exemplary molecular weights of small molecule drugs include molecularweights of: less than about 950; less than about 900; less than about850; less than about 800; less than about 750; less than about 700; lessthan about 650; less than about 600; less than about 550; less thanabout 500; less than about 450; less than about 400; less than about350; and less than about 300 Daltons.

The small molecule drug used in the invention, if chiral, may beobtained from a racemic mixture, or an optically active form, forexample, a single optically active enantiomer, or any combination orratio of enantiomers (i.e., scalemic mixture). In addition, the smallmolecule drug may possess one or more geometric isomers. With respect togeometric isomers, a composition can comprise a single geometric isomeror a mixture of two or more geometric isomers. A small molecule drug foruse in the present invention can be in its customary active form, or maypossess some degree of modification. For example, a small molecule drugmay have a targeting agent, tag, or transporter attached thereto, priorto or after covalent attachment of an oligomer. Alternatively, the smallmolecule drug may possess a lipophilic moiety attached thereto, such asa phospholipid (e.g., distearoylphosphatidylethanolamine or “DSPE,”dipalmitoylphosphatidylethanolamine or “DPPE,” and so forth) or a smallfatty acid. In some instances, however, it is preferred that the smallmolecule drug moiety does not include attachment to a lipophilic moiety.

The opioid diarylpiperazine moiety for coupling to a water-soluble,non-peptidic oligomer possesses a free hydroxyl, carboxyl, thio, aminogroup, or the like (i.e., “handle”) suitable for covalent attachment tothe oligomer. In addition, the opioid diarylpiperazine moiety may bemodified by introduction of a reactive group, preferably by conversionof one of its existing functional groups to a functional group suitablefor formation of a stable covalent linkage between the oligomer and thedrug.

Accordingly, each oligomer is composed of up to three different monomertypes selected from the group consisting of: alkylene oxide, such asethylene oxide or propylene oxide; olefinic alcohol, such as vinylalcohol, 1-propenol or 2-propenol; vinyl pyrrolidone; hydroxyalkylmethacrylamide or hydroxyalkyl methacrylate, where alkyl is preferablymethyl; α-hydroxy acid, such as lactic acid or glycolic acid;phosphazene, oxazoline, amino acids, carbohydrates such asmonosaccharides, alditol such as mannitol; and N-acryloylmorpholine.Preferred monomer types include alkylene oxide, olefinic alcohol,hydroxyalkyl methacrylamide or methacrylate, N-acryloylmorpholine, andα-hydroxy acid. Preferably, each oligomer is, independently, aco-oligomer of two monomer types selected from this group, or, morepreferably, is a homo-oligomer of one monomer type selected from thisgroup.

The two monomer types in a co-oligomer may be of the same monomer type,for example, two alkylene oxides, such as ethylene oxide and propyleneoxide. Preferably, the oligomer is a homo-oligomer of ethylene oxide.Usually, although not necessarily, the terminus (or termini) of theoligomer that is not covalently attached to a small molecule is cappedto render it unreactive. Alternatively, the terminus may include areactive group. When the terminus is a reactive group, the reactivegroup is either selected such that it is unreactive under the conditionsof formation of the final oligomer or during covalent attachment of theoligomer to a small molecule drug, or it is protected as necessary. Onecommon end-functional group is hydroxyl or —OH, particularly foroligoethylene oxides.

The water-soluble, non-peptidic oligomer (e.g., “POLY” in variousstructures provided herein) can have any of a number of differentgeometries. For example, the water-soluble, non-peptidic oligomer can belinear, branched, or forked. Most typically, the water-soluble,non-peptidic oligomer is linear or is branched, for example, having onebranch point. Although much of the discussion herein is focused uponpoly(ethylene oxide) as an illustrative oligomer, the discussion andstructures presented herein can be readily extended to encompass anywater-soluble, non-peptidic oligomers described above.

The molecular weight of the water-soluble, non-peptidic oligomer,excluding the linker portion, is generally relatively low. Exemplaryvalues of the molecular weight of the water-soluble polymer include:below about 1500; below about 1450; below about 1400; below about 1350;below about 1300; below about 1250; below about 1200; below about 1150;below about 1100; below about 1050; below about 1000; below about 950;below about 900; below about 850; below about 800; below about 750;below about 700; below about 650; below about 600; below about 550;below about 500; below about 450; below about 400; below about 350;below about 300; below about 250; below about 200; and below about 100Daltons.

Exemplary ranges of molecular weights of the water-soluble, non-peptidicoligomer (excluding the linker) include: from about 100 to about 1400Daltons; from about 100 to about 1200 Daltons; from about 100 to about800 Daltons; from about 100 to about 500 Daltons; from about 100 toabout 400 Daltons; from about 200 to about 500 Daltons; from about 200to about 400 Daltons; from about 75 to 1000 Daltons; and from about 75to about 750 Daltons.

Preferably, the number of monomers in the water-soluble, non-peptidicoligomer falls within one or more of the following ranges: between about1 and about 30 (inclusive); between about 1 and about 25; between about1 and about 20; between about 1 and about 15; between about 1 and about12; between about 1 and about 10. In certain instances, the number ofmonomers in series in the oligomer (and the corresponding conjugate) isone of 1, 2, 3, 4, 5, 6, 7, or 8. In additional embodiments, theoligomer (and the corresponding conjugate) contains 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, or 20 monomers. In yet further embodiments, theoligomer (and the corresponding conjugate) possesses 21, 22, 23, 24, 25,26, 27, 28, 29 or 30 monomers in series. Thus, for example, when thewater-soluble, non-peptidic polymer includes CH₃—(OCH₂CH₂)_(n)—, “n” isan integer that can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, andcan fall within one or more of the following ranges: between about 1 andabout 25; between about 1 and about 20; between about 1 and about 15;between about 1 and about 12; between about 1 and about 10.

When the water-soluble, non-peptidic oligomer has 1, 2, 3, 4, 5, 6, 7,8, 9, or monomers, these values correspond to a methoxy end-cappedoligo(ethylene oxide) having a molecular weights of about 75, 119, 163,207, 251, 295, 339, 383, 427, and 471 Daltons, respectively. When theoligomer has 11, 12, 13, 14, or 15 monomers, these values correspond tomethoxy end-capped oligo(ethylene oxide) having molecular weightscorresponding to about 515, 559, 603, 647, and 691 Daltons,respectively.

When the water-soluble, non-peptidic oligomer is attached to the opioiddiarylpiperazine (in contrast to the step-wise addition of one or moremonomers to effectively “grow” the oligomer onto the opioiddiarylpiperazine), it is preferred that the composition containing anactivated form of the water-soluble, non-peptidic oligomer bemonodisperse. In those instances, however, where a bimodal compositionis employed, the composition will possess a bimodal distributioncentering around any two of the above numbers of monomers. For instance,a bimodal oligomer may have any one of the following exemplarycombinations of monomer subunits: 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, and so forth; 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-10, and soforth; 3-4, 3-5, 3-6, 3-7, 3-8, 3-9, 3-10, and so forth; 4-5, 4-6, 4-7,4-8, 4-9, 4-10, and so forth; 5-6, 5-7, 5-8, 5-9, 5-10, and so forth;6-7, 6-8, 6-9, 6-10, and so forth; 7-8, 7-9, 7-10, and so forth; and8-9, 8-10, and so forth.

In some instances, the composition containing an activated form of thewater-soluble, non-peptidic oligomer will be trimodal or eventetramodal, possessing a range of monomers units as previouslydescribed. Oligomer compositions possessing a well-defined mixture ofoligomers (i.e., being bimodal, trimodal, tetramodal, and so forth) canbe prepared by mixing purified monodisperse oligomers to obtain adesired profile of oligomers (a mixture of two oligomers differing onlyin the number of monomers is bimodal; a mixture of three oligomersdiffering only in the number of monomers is trimodal; a mixture of fouroligomers differing only in the number of monomers is tetramodal), oralternatively, can be obtained from column chromatography of apolydisperse oligomer by recovering the “center cut”, to obtain amixture of oligomers in a desired and defined molecular weight range.

It is preferred that the water-soluble, non-peptidic oligomer isobtained from a composition that is preferably unimolecular ormonodisperse. That is, the oligomers in the composition possess the samediscrete molecular weight value rather than a distribution of molecularweights. Some monodisperse oligomers can be purchased from commercialsources such as those available from Sigma-Aldrich, or alternatively,can be prepared directly from commercially available starting materialssuch as Sigma-Aldrich. Water-soluble, non-peptidic oligomers can beprepared as described in Chen Y., Baker, G. L., J. Org. Chem., 6870-6873(1999), WO 02/098949, and U.S. Patent Application Publication2005/0136031.

When present, the spacer moiety (through which the water-soluble,non-peptidic polymer is attached to the opioid diarylpiperazine moiety)may be a single bond, a single atom, such as an oxygen atom or a sulfuratom, two atoms, or a number of atoms. A spacer moiety is typically butis not necessarily linear in nature. The spacer moiety, “X,” ishydrolytically stable, and is preferably also enzymatically stable.Preferably, the spacer moiety “X” is one having a chain length of lessthan about 12 atoms, and preferably less than about 10 atoms, and evenmore preferably less than about 8 atoms and even more preferably lessthan about 5 atoms, whereby length is meant the number of atoms in asingle chain, not counting substituents. For instance, a urea linkagesuch as this, R_(oligomer)—NH—(C═O)—NH—R′_(drug), is considered to havea chain length of 3 atoms (—NH—C(O)—NH—). In selected embodiments, thelinkage does not comprise further spacer groups.

In some instances, the spacer moiety “X” comprises an ether, amide,urethane, amine, thioether, urea, or a carbon-carbon bond. Functionalgroups such as those discussed below, and illustrated in the examples,are typically used for forming the linkages. The spacer moiety may lesspreferably also comprise (or be adjacent to or flanked by) other atoms,as described further below.

More specifically, in selected embodiments, a spacer moiety of theinvention, X, may be any of the following: “—” (i.e., a covalent bond,that may be stable or degradable, between the opioid diarylpiperazineresidue and the water-soluble, non-peptidic oligomer),), —O—, —NH—, —S—,—C(O)—, —C(O)O—, —OC(O)—, —CH₂—C(O)O—, —CH₂—OC(O)—, —C(O)O—CH₂—,—OC(O)—CH₂—, C(O)—NH, NH—C(O)—NH, O—C(O)—NH, —C(S)—, —CH₂—, —CH₂—CH₂—,—CH₂—CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—, /—O—CH₂—, —CH₂—O—, —O—CH₂—CH₂—,—CH₂—O—CH₂—, —CH₂—CH₂—O—, —O—CH₂—CH₂—CH₂—, —CH₂—O—CH₂—CH₂—,—CH₂—CH₂—O—CH₂—, —CH₂—CH₂—CH₂—O—, —O—CH₂—CH₂—CH₂—CH₂—,—CH₂—O—CH₂—CH₂—CH₂—, —CH₂—CH₂—O—CH₂—CH₂—, —CH₂—CH₂—CH₂—O—CH₂—,—CH₂—CH₂—CH₂—CH₂—O—, —C(O)—NH—CH₂—, —C(O)—NH—CH₂—CH₂—,—CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—C(O)—NH—, —C(O)—NH—C H₂—CH₂—CH₂—,—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—,—C(O)—NH—CH₂—CH₂—CH₂—CH₂—, —CH₂—C(O)—NH—CH₂—CH₂—CH₂—,—CH₂—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—,—CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—C(O)—NH—NH—C(O)—CH₂—,—CH₂—NH—C(O)—CH₂—, —CH₂—CH₂—NH—C(O)—CH₂—, —NH—C(O)—CH₂—CH₂—,—CH₂—NH—C(O)—CH₂—CH₂, —CH₂—CH₂—NH—C(O)—CH₂—CH₂, —C(O)—NH—CH₂—,—C(O)—NH—CH₂—CH₂—, —O—C(O)—NH—CH₂—, —O—C(O)—N H—CH₂—CH₂—, —NH—CH₂—,—NH—CH₂—CH₂—, —CH₂—NH—CH₂—, —CH₂—CH₂—NH—CH₂—, —C(O)—CH₂—,—C(O)—CH₂—CH₂—, —CH₂—C(O)—CH₂—, —CH₂—CH₂—C(O)—CH₂—,—CH₂—CH₂—C(O)—CH₂—CH₂—, —CH₂—CH₂—C(O)—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—C(O)—,—CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—C(O)—CH₂—, bivalent cycloalkyl group,—N(R⁶)—, R⁶ is H or an organic radical selected from the groupconsisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl,alkynyl, substituted alkynyl, aryl and substituted aryl. Additionalspacer moieties include, acylamino, acyl, aryloxy, alkylene bridgecontaining between 1 and 5 inclusive carbon atoms, alkylamino,dialkylamino having about 2 to 4 inclusive carbon atoms, piperidino,pyrrolidino, N-(lower alkyl)-2-piperidyl, morpholino, 1-piperizinyl,4-(lower alkyl)-1-piperizinyl, 4-(hydroxyl-lower alkyl)-1-piperizinyl,4-(methoxy-lower alkyl)-1-piperizinyl, and guanidine. In some instances,a portion or a functional group of the drug compound may be modified orremoved altogether to facilitate attachment of the oligomer. In someinstances, it is preferred that X is not an amide, i.e., —CONR— or—RNCO—).

For purposes of the present invention, however, a group of atoms is notconsidered a linkage when it is immediately adjacent to an oligomersegment, and the group of atoms is the same as a monomer of the oligomersuch that the group would represent a mere extension of the oligomerchain.

The linkage “X” between the water-soluble, non-peptidic oligomer and thesmall molecule is typically formed by reaction of a functional group ona terminus of the oligomer (or nascent oligomer when it is desired to“grow” the oligomer onto the opioid diarylpiperazine) with acorresponding functional group within the opioid diarylpiperazine.Illustrative reactions are described briefly below. For example, anamino group on an oligomer may be reacted with a carboxylic acid or anactivated carboxylic acid derivative on the small molecule, or viceversa, to produce an amide linkage. Alternatively, reaction of an amineon an oligomer with an activated carbonate (e.g. succinimidyl orbenzotriazolyl carbonate) on the drug, or vice versa, forms a carbamatelinkage. Reaction of an amine on an oligomer with an isocyanate(R—N═C═O) on a drug, or vice versa, forms a urea linkage(R—NH—(C═O)—NH—R′). Further, reaction of an alcohol (alkoxide) group onan oligomer with an alkyl halide, or halide group within a drug, or viceversa, forms an ether linkage. In yet another coupling approach, a smallmolecule having an aldehyde function is coupled to an oligomer aminogroup by reductive amination, resulting in formation of a secondaryamine linkage between the oligomer and the small molecule.

A particularly preferred water-soluble, non-peptidic oligomer is anoligomer bearing an aldehyde functional group. In this regard, theoligomer will have the following structure:CH₃O—(CH₂—CH₂—O)_(n)—(CH₂)_(p)—C(O)H, wherein (n) is one of 1, 2, 3, 4,5, 6, 7, 8, 9 and 10 and (p) is one of 1, 2, 3, 4, 5, 6 and 7. Preferred(n) values include 3, 5 and 7 and preferred (p) values 2, 3 and 4.

The termini of the water-soluble, non-peptidic oligomer not bearing afunctional group may be capped to render it unreactive. When theoligomer includes a further functional group at a terminus other thanthat intended for formation of a conjugate, that group is eitherselected such that it is unreactive under the conditions of formation ofthe linkage “X,” or it is protected during the formation of the linkage“X.”

As stated above, the water-soluble, non-peptidic oligomer includes atleast one functional group prior to conjugation. The functional grouptypically comprises an electrophilic or nucleophilic group for covalentattachment to a small molecule, depending upon the reactive groupcontained within or introduced into the small molecule. Examples ofnucleophilic groups that may be present in either the oligomer or thesmall molecule include hydroxyl, amine, hydrazine (—NHNH₂), hydrazide(—C(O)NHNH₂), and thiol. Preferred nucleophiles include amine,hydrazine, hydrazide, and thiol, particularly amine. Most small moleculedrugs for covalent attachment to an oligomer will possess a freehydroxyl, amino, thio, aldehyde, ketone, or carboxyl group.

Examples of electrophilic functional groups that may be present ineither the oligomer or the small molecule include carboxylic acid,carboxylic ester, particularly imide esters, orthoester, carbonate,isocyanate, isothiocyanate, aldehyde, ketone, thione, alkenyl, acrylate,methacrylate, acrylamide, sulfone, maleimide, disulfide, iodo, epoxy,sulfonate, thiosulfonate, silane, alkoxysilane, and halosilane. Morespecific examples of these groups include succinimidyl ester orcarbonate, imidazoyl ester or carbonate, benzotriazole ester orcarbonate, vinyl sulfone, chloroethylsulfone, vinylpyridine, pyridyldisulfide, iodoacetamide, glyoxal, dione, mesylate, tosylate, andtresylate (2,2,2-trifluoroethanesulfonate).

Also included are sulfur analogs of several of these groups, such asthione, thione hydrate, thioketal, 2-thiazolidine thione, etc., as wellas hydrates or protected derivatives of any of the above moieties (e.g.aldehyde hydrate, hemiacetal, acetal, ketone hydrate, hemiketal, ketal,thioketal, thioacetal).

An “activated derivative” of a carboxylic acid refers to a carboxylicacid derivative that reacts readily with nucleophiles, generally muchmore readily than the underivatized carboxylic acid. Activatedcarboxylic acids include, for example, acid halides (such as acidchlorides), anhydrides, carbonates, and esters. Such esters includeimide esters, of the general form —(CO)O—N[(CO)—]₂; for example,N-hydroxysuccinimidyl (NHS) esters or N-hydroxyphthalimidyl esters. Alsopreferred are imidazolyl esters and benzotriazole esters. Particularlypreferred are activated propionic acid or butanoic acid esters, asdescribed in co-owned U.S. Pat. No. 5,672,662. These include groups ofthe form —(CH₂)₂₋₃C(═O))-Q, where Q is preferably selected fromN-succinimide, N-sulfosuccinimide, N-phthalimide, N-glutarimide,N-tetrahydrophthalimide, N-norbornene-2,3-dicarboximide, benzotriazole,7-azabenzotriazole, and imidazole.

Other preferred electrophilic groups include succinimidyl carbonate,maleimide, benzotriazole carbonate, glycidyl ether, imidazoyl carbonate,p-nitrophenyl carbonate, acrylate, tresylate, aldehyde, and orthopyridyldisulfide.

These electrophilic groups are subject to reaction with nucleophiles,e.g., hydroxy, thio, or amino groups, to produce various bond types.Preferred for the present invention are reactions which favor formationof a hydrolytically stable linkage. For example, carboxylic acids andactivated derivatives thereof, which include orthoesters, succinimidylesters, imidazolyl esters, and benzotriazole esters, react with theabove types of nucleophiles to form esters, thioesters, and amides,respectively, of which amides are the most hydrolytically stable.Carbonates, including succinimidyl, imidazolyl, and benzotriazolecarbonates, react with amino groups to form carbamates. Isocyanates(R—N═C═O) react with hydroxyl or amino groups to form, respectively,carbamate (RNH—C(O)—OR′) or urea (RNH—C(O)—NHR′) linkages. Aldehydes,ketones, glyoxals, diones and their hydrates or alcohol adducts (i.e.,aldehyde hydrate, hemiacetal, acetal, ketone hydrate, hemiketal, andketal) are preferably reacted with amines, followed by reduction of theresulting imine, if desired, to provide an amine linkage (reductiveamination).

Several of the electrophilic functional groups include electrophilicdouble bonds to which nucleophilic groups, such as thiols, can be added,to form, for example, thioether bonds. These groups include maleimides,vinyl sulfones, vinyl pyridine, acrylates, methacrylates, andacrylamides. Other groups comprise leaving groups that can be displacedby a nucleophile; these include chloroethyl sulfone, pyridyl disulfides(which include a cleavable S—S bond), iodoacetamide, mesylate, tosylate,thiosulfonate, and tresylate. Epoxides react by ring opening by anucleophile, to form, for example, an ether or amine bond. Reactionsinvolving complementary reactive groups such as those noted above on theoligomer and the small molecule are utilized to prepare the conjugatesof the invention.

In some instances the opioid diarylpiperazine may not have a functionalgroup suited for conjugation. In this instance, it is possible to modify(or “functionalize”) the “original” opioid diarylpiperazine so that itdoes have a functional group suited for conjugation. For example, if theopioid diarylpiperazine has an amide group, but an amine group isdesired, it is possible to modify the amide group to an amine group byway of a Hofmann rearrangement, Curtius rearrangement (once the amide isconverted to an azide) or Lossen rearrangement (once amide is concertedto hydroxamide followed by treatment with tolyene-2-sulfonylchloride/base).

It is possible to prepare a conjugate of small molecule opioiddiarylpiperazine bearing a carboxyl group wherein the carboxylgroup-bearing small molecule opioid diarylpiperazine is coupled to anamino-terminated oligomeric ethylene glycol, to provide a conjugatehaving an amide group covalently linking the small molecule opioiddiarylpiperazine to the oligomer. This can be performed, for example, bycombining the carboxyl group-bearing small molecule opioiddiarylpiperazine with the amino-terminated oligomeric ethylene glycol inthe presence of a coupling reagent, (such as dicyclohexylcarbodiimide or“DCC”) in an anhydrous organic solvent.

Further, it is possible to prepare a conjugate of a small moleculeopioid diarylpiperazine bearing a hydroxyl group wherein the hydroxylgroup-bearing small molecule opioid diarylpiperazine is coupled to anoligomeric ethylene glycol halide to result in an ether (—O—) linkedsmall molecule conjugate. This can be performed, for example, by usingsodium hydride to deprotonate the hydroxyl group followed by reactionwith a halide-terminated oligomeric ethylene glycol.

Further, it is possible to prepare a conjugate of a small moleculeopioid diarylpiperazine moiety bearing a hydroxyl group wherein thehydroxyl group-bearing small molecule opioid diarylpiperazine moiety iscoupled to an oligomeric ethylene glycol bearing an haloformate group[e.g., CH₃(OCH₂CH₂)_(n)OC(O)-halo, where halo is chloro, bromo, iodo] toresult in a carbonate [—O—C(O)—O—] linked small molecule conjugate. Thiscan be performed, for example, by combining an opioid diarylpiperazinemoiety and an oligomeric ethylene glycol bearing a haloformate group inthe presence of a nucleophilic catalyst (such as 4-dimethylaminopyridineor “DMAP”) to thereby result in the corresponding carbonate-linkedconjugate.

In another example, it is possible to prepare a conjugate of a smallmolecule opioid diarylpiperazine bearing a ketone group by firstreducing the ketone group to form the corresponding hydroxyl group.Thereafter, the small molecule opioid diarylpiperazine now bearing ahydroxyl group can be coupled as described herein.

In still another instance, it is possible to prepare a conjugate of asmall molecule opioid diarylpiperazine bearing an amine group. In oneapproach, the amine group-bearing small molecule opioid diarylpiperazineand an aldehyde-bearing oligomer are dissolved in a suitable bufferafter which a suitable reducing agent (e.g., NaCNBH₃) is added.Following reduction, the result is an amine linkage formed between theamine group of the amine group-containing small molecule opioiddiarylpiperazine and the carbonyl carbon of the aldehyde-bearingoligomer.

In another approach for preparing a conjugate of a small molecule opioiddiarylpiperazine bearing an amine group, a carboxylic acid-bearingoligomer and the amine group-bearing small molecule opioiddiarylpiperazine are combined, typically in the presence of a couplingreagent (e.g., DCC). The result is an amide linkage formed between theamine group of the amine group-containing small molecule opioiddiarylpiperazine and the carbonyl of the carboxylic acid-bearingoligomer.

While it is believed that the full scope of the conjugates disclosedherein behave as described, an optimally sized oligomer can beidentified as follows.

First, an oligomer obtained from a monodisperse or bimodal water solubleoligomer is conjugated to the small molecule drug. Preferably, the drugis orally bioavailable, and on its own, exhibits a non-negligibleblood-brain barrier crossing rate. Next, the ability of the conjugate tocross the blood-brain barrier is determined using an appropriate modeland compared to that of the unmodified parent drug. If the results arefavorable, that is to say, if, for example, the rate of crossing issignificantly reduced, then the bioactivity of conjugate is furtherevaluated. Preferably, the compounds according to the invention maintaina significant degree of bioactivity relative to the parent drug, i.e.,greater than about 30% of the bioactivity of the parent drug, or evenmore preferably, greater than about 50% of the bioactivity of the parentdrug.

The above steps are repeated one or more times using oligomers of thesame monomer type but having a different number of subunits and theresults compared.

For each conjugate whose ability to cross the blood-brain barrier isreduced in comparison to the non-conjugated small molecule drug, itsoral bioavailability is then assessed. Based upon these results, that isto say, based upon the comparison of conjugates of oligomers of varyingsize to a given small molecule at a given position or location withinthe small molecule, it is possible to determine the size of the oligomermost effective in providing a conjugate having an optimal balancebetween reduction in biological membrane crossing, oral bioavailability,and bioactivity. The small size of the oligomers makes such screeningsfeasible and allows one to effectively tailor the properties of theresulting conjugate. By making small, incremental changes in oligomersize and utilizing an experimental design approach, one can effectivelyidentify a conjugate having a favorable balance of reduction inbiological membrane crossing rate, bioactivity, and oralbioavailability. In some instances, attachment of an oligomer asdescribed herein is effective to actually increase oral bioavailabilityof the drug.

For example, one of ordinary skill in the art, using routineexperimentation, can determine a best suited molecular size and linkagefor improving oral bioavailability by first preparing a series ofoligomers with different weights and functional groups and thenobtaining the necessary clearance profiles by administering theconjugates to a patient and taking periodic blood and/or urine sampling.Once a series of clearance profiles have been obtained for each testedconjugate, a suitable conjugate can be identified.

Animal models (rodents and dogs) can also be used to study oral drugtransport. In addition, non-in vivo methods include rodent everted gutexcised tissue and Caco-2 cell monolayer tissue-culture models. Thesemodels are useful in predicting oral drug bioavailability.

To determine whether the opioid diarylpiperazine or the conjugate of anopioid diarylpiperazine and a water-soluble non-peptidic polymer hasactivity as an opioid diarylpiperazine therapeutic, it is possible totest such a compound. The opioid diarylpiperazine compounds may betested using in vitro binding studies to receptors using various celllines expressing these receptors that have become routine inpharmaceutical industry. For example, Befort et al., describe thefollowing assay:

Expression of Wild-Type mDOR and Mutant Receptors in COS Cells andLigand Binding

COS-1 cells (1.5×10⁶ cells/140-mm dish) were transfected with purifiedplasmids (35 μg/dish) using the DEAE-dextran method. After 72 hoursgrowth in Dulbecco's modified Eagle's medium with 10% fetal calf serum,the cells were harvested and membranes were prepared. For bindingexperiments, various amounts of membrane proteins of mDOR and mutantreceptors, ranging from 20 to 100 μg, were diluted in 50 mM Tris-HCl, pH7.4, and incubated for 1 hour at 25° C. with opioid ligands in a finalvolume of 0.5 ml. For saturation experiments, eight concentrations of[³H]diprenorphine ranging from 0.05 to 10 nM (for WT, Y129F, W173A,F218A, Y308F) and eight concentrations of [³H]naltrindole ranging from0.1 to 12 nM (for WT, Y129A, F222A, W274A) were used. Nonspecificbinding was determined in the presence of 2 μM (for WT and F218A), 0.1mM (for Y129F, W173A, and Y308F), or 0.5 mM (for Y129A, F222A, andW274A) naloxone. For competition studies, membrane preparations wereincubated with [³H]diprenorphine (1 nM for WT, Y129F, F218A and 2 nM forW173A and Y308F) or [³H]naltrindole (2 nM for Y129A, F222A, Y308F), inthe presence of variable concentrations of opioid competing ligands.When using endogenous peptides as competitors, assays were conducted inthe presence of a mixture of protease inhibitors (leupeptin, pepstatin,aprotinin, antipain, and chymostatin, each at 2.5 mg/ml). K_(d), K_(i),and B_(max), values were calculated using the EBDA/Ligand program (G. A.McPherson, Biosoft, Cambridge, United Kingdom).

Binding characteristics for various receptors including, but not limitedto, delta, kappa, and mu opioid receptors are determined. Arepresentative data set using positive and negative controls is shownbelow.

Delta Opioid Receptor Binding:

Kd (binding affinity) Forebrain Bmax 2.1E−9 Ligand 4.5 fmol/mg tissue(wet weight) Ligand (M) [3H]Enkephalin, DPDPE Non-Specific 1E−9Reference Compound 1E−6 Method DPDPE Measurement RadioactivityNon-specific (M) DPDPE

Further, concerning specific receptor ligands, the distinction betweendelta receptor agonists and antagonists is made by their activity in theelectrically stimulated mouse vas deferens assay, which typically hasbeen considered the appropriate diagnostic tissue for the deltareceptor. By contrast, mu receptor agonists are generally characterizedby their activity in the electrically stimulated guinea pig ileum assay.Thus, conjugates of the present invention and other compounds maysuitably be tested in such assays. For example, U.S. Pat. No. 5,658,908provides following assays:

In vitro bioassays: Vasa deferentia are removed from mice and suspendedbetween platinum electrodes with 0.5 g of tension in organ bath chamberscontaining a modified Krebs' buffer of the following composition(millimolar): NaCl, 118; KCl, 4.75; CaCl.sub.2, 2.6; KH.sub.2 PO.sub.4,1.20; NaHCO.sub.3, 24.5; and glucose, 11. The buffer is saturated with95% O₂/5% CO₂ and kept at 37° C. Tissues are stimulated at supramaximalvoltage with 10 Hz pulse trains for 400 msec; train interval 10 seconds;and 0.5 msec pulse duration. Intact ileums (about 3 cm length) areremoved from guinea pig and suspended with 1 g of tension in a bathchamber as described. The modified Krebs' buffer also contained MgSO₄(1.2 mM). The ileums are stimulated with electrical square-wave pulsesof 0.1 Hz, 0.5 msec pulse duration at supramaximal voltage. Thepercentage inhibition of the electrically induced muscle contractions isdetermined for the compounds at varying cumulative concentrations. TheED₅₀ values are extrapolated from curves showing the dose concentrationplotted against the response (J. A. H. Lord, A. A. Waterfield, J.Hughes, H. W. Kosterlitz, Nature 267, 495, (1977)).

Inhibition of receptor binding: Rat (Sprague-Dawley) brain membranes areprepared and binding assays are performed at 24° C. for 60 min. asdescribed by Chang, et. al (J. Biol. Chem. 254, 2610 (1979) and Mol.Pharmacol. 16, 91 (1979)) with a filtration method (GF/C filter). Deltareceptor binding assays are performed with ¹²⁵I-labeled [D-Ala², D-Leu⁵]enkephalin (0.24 nM) in the presence of the highly selective mu-agonist[N—MePhe³, D-Pro⁴] morphiceptin to suppress mu-receptorcross-reactivity. Mu receptor binding assays are performed with¹²⁵I-labeled [D-Ala², N—MePhe⁴, Met(O)ol⁵] enkephalin (0.1 nM).Non-specific binding is determined in the presence of 1 μM of therespective unlabeled ligand. The potency of compounds in inhibiting thebinding of ¹²⁵I-labeled enkephalin analogs is determined as theconcentration which reduced the binding of the labeled compounds by 50percent (IC₅₀).

The present invention also includes pharmaceutical preparationscomprising a conjugate as provided herein in combination with apharmaceutical excipient. Generally, the conjugate itself will be in asolid form (e.g., a precipitate), which can be combined with a suitablepharmaceutical excipient that can be in either solid or liquid form.

Exemplary excipients include, without limitation, those selected fromthe group consisting of carbohydrates, inorganic salts, antimicrobialagents, antioxidants, surfactants, buffers, acids, bases, andcombinations thereof.

A carbohydrate such as a sugar, a derivatized sugar such as an alditol,aldonic acid, an esterified sugar, and/or a sugar polymer may be presentas an excipient. Specific carbohydrate excipients include, for example:monosaccharides, such as fructose, maltose, galactose, glucose,D-mannose, sorbose, and the like; disaccharides, such as lactose,sucrose, trehalose, cellobiose, and the like; polysaccharides, such asraffinose, melezitose, maltodextrins, dextrans, starches, and the like;and alditols, such as mannitol, maltitol, lactitol, xylitol, sorbitol,myoinositol, and the like.

The excipient can also include an inorganic salt or buffer such ascitric acid, sodium chloride, potassium chloride, sodium sulfate,potassium nitrate, sodium phosphate monobasic, sodium phosphate dibasic,and combinations thereof.

The preparation may also include an antimicrobial agent for preventingor deterring microbial growth. Nonlimiting examples of antimicrobialagents suitable for the present invention include benzalkonium chloride,benzethonium chloride, benzyl alcohol, cetylpyridinium chloride,chlorobutanol, phenol, phenylethyl alcohol, phenylmercuric nitrate,thimersol, and combinations thereof.

An antioxidant can be present in the preparation as well. Antioxidantsare used to prevent oxidation, thereby preventing the deterioration ofthe conjugate or other components of the preparation. Suitableantioxidants for use in the present invention include, for example,ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene,hypophosphorous acid, monothioglycerol, propyl gallate, sodiumbisulfite, sodium formaldehyde sulfoxylate, sodium metabisulfite, andcombinations thereof.

A surfactant may be present as an excipient. Exemplary surfactantsinclude: polysorbates, such as “Tween 20” and “Tween 80,” and pluronicssuch as F68 and F88 (both of which are available from BASF, Mount Olive,N.J.); sorbitan esters; lipids, such as phospholipids such as lecithinand other phosphatidylcholines, phosphatidylethanolamines, fatty acidsand fatty esters; steroids, such as cholesterol; and chelating agents,such as EDTA, zinc and other such suitable cations.

Pharmaceutically acceptable acids or bases may be present as anexcipient in the preparation. Nonlimiting examples of acids that can beused include those acids selected from the group consisting ofhydrochloric acid, acetic acid, phosphoric acid, citric acid, malicacid, lactic acid, formic acid, trichloroacetic acid, nitric acid,perchloric acid, phosphoric acid, sulfuric acid, fumaric acid, andcombinations thereof. Examples of suitable bases include, withoutlimitation, bases selected from the group consisting of sodiumhydroxide, sodium acetate, ammonium hydroxide, potassium hydroxide,ammonium acetate, potassium acetate, sodium phosphate, potassiumphosphate, sodium citrate, sodium formate, sodium sulfate, potassiumsulfate, potassium fumerate, and combinations thereof.

The amount of the conjugate in the composition will vary depending on anumber of factors, but will optimally be a therapeutically effectivedose when the composition is stored in a unit dose container. Atherapeutically effective dose can be determined experimentally byrepeated administration of increasing amounts of the conjugate in orderto determine which amount produces a clinically desired endpoint.

The amount of any individual excipient in the composition will varydepending on the activity of the excipient and particular needs of thecomposition. Typically, the optimal amount of any individual excipientis determined through routine experimentation, i.e., by preparingcompositions containing varying amounts of the excipient (ranging fromlow to high), examining the stability and other parameters, and thendetermining the range at which optimal performance is attained with nosignificant adverse effects.

Generally, however, excipients will be present in the composition in anamount of about 1% to about 99% by weight, preferably from about 5%-98%by weight, more preferably from about 15-95% by weight of the excipient,with concentrations less than 30% by weight most preferred.

These foregoing pharmaceutical excipients along with other excipientsand general teachings regarding pharmaceutical compositions aredescribed in “Remington: The Science & Practice of Pharmacy”, 19^(th)ed., Williams & Williams, (1995), the “Physician's Desk Reference”,52^(nd) ed., Medical Economics, Montvale, N.J. (1998), and Kibbe, A. H.,Handbook of Pharmaceutical Excipients, 3^(rd) Edition, AmericanPharmaceutical Association, Washington, D.C., 2000.

The pharmaceutical compositions can take any number of forms and theinvention is not limited in this regard. Exemplary preparations are mostpreferably in a form suitable for oral administration such as a tablet,caplet, capsule, gel cap, troche, dispersion, suspension, solution,elixir, syrup, lozenge, transdermal patch, spray, suppository, andpowder.

Oral dosage forms are preferred for those conjugates that are orallyactive, and include tablets, caplets, capsules, gel caps, suspensions,solutions, elixirs, and syrups, and can also comprise a plurality ofgranules, beads, powders or pellets that are optionally encapsulated.Such dosage forms are prepared using conventional methods known to thosein the field of pharmaceutical formulation and described in thepertinent texts.

Tablets and caplets, for example, can be manufactured using standardtablet processing procedures and equipment. Direct compression andgranulation techniques are preferred when preparing tablets or capletscontaining the conjugates described herein. In addition to theconjugate, the tablets and caplets will generally contain inactive,pharmaceutically acceptable carrier materials such as binders,lubricants, disintegrants, fillers, stabilizers, surfactants, coloringagents, flow agents, and the like. Binders are used to impart cohesivequalities to a tablet, and thus ensure that the tablet remains intact.Suitable binder materials include, but are not limited to, starch(including corn starch and pregelatinized starch), gelatin, sugars(including sucrose, glucose, dextrose and lactose), polyethylene glycol,waxes, and natural and synthetic gums, e.g., acacia sodium alginate,polyvinylpyrrolidone, cellulosic polymers (including hydroxypropylcellulose, hydroxypropyl methylcellulose, methyl cellulose,microcrystalline cellulose, ethyl cellulose, hydroxyethylcellulose, andthe like), and Veegum. Lubricants are used to facilitate tabletmanufacture, promoting powder flow and preventing particle capping(i.e., particle breakage) when pressure is relieved. Useful lubricantsare magnesium stearate, calcium stearate, and stearic acid.Disintegrants are used to facilitate disintegration of the tablet, andare generally starches, clays, celluloses, algins, gums, or crosslinkedpolymers. Fillers include, for example, materials such as silicondioxide, titanium dioxide, alumina, talc, kaolin, powdered cellulose,and microcrystalline cellulose, as well as soluble materials such asmannitol, urea, sucrose, lactose, dextrose, sodium chloride, andsorbitol. Stabilizers, as well known in the art, are used to inhibit orretard drug decomposition reactions that include, by way of example,oxidative reactions.

Capsules are also preferred oral dosage forms, in which case theconjugate-containing composition can be encapsulated in the form of aliquid or gel (e.g., in the case of a gel cap) or solid (includingparticulates such as granules, beads, powders or pellets). Suitablecapsules include hard and soft capsules, and are generally made ofgelatin, starch, or a cellulosic material. Two-piece hard gelatincapsules are preferably sealed, such as with gelatin bands or the like.

Included are parenteral formulations in the substantially dry form(typically as a lyophilizate or precipitate, which can be in the form ofa powder or cake), as well as formulations prepared for injection, whichare typically liquid and requires the step of reconstituting the dryform of parenteral formulation. Examples of suitable diluents forreconstituting solid compositions prior to injection includebacteriostatic water for injection, dextrose 5% in water,phosphate-buffered saline, Ringer's solution, saline, sterile water,deionized water, and combinations thereof.

In some cases, compositions intended for parenteral administration cantake the form of nonaqueous solutions, suspensions, or emulsions, eachtypically being sterile. Examples of nonaqueous solvents or vehicles arepropylene glycol, polyethylene glycol, vegetable oils, such as olive oiland corn oil, gelatin, and injectable organic esters such as ethyloleate.

The parenteral formulations described herein can also contain adjuvantssuch as preserving, wetting, emulsifying, and dispersing agents. Theformulations are rendered sterile by incorporation of a sterilizingagent, filtration through a bacteria-retaining filter, irradiation, orheat.

The conjugate can also be administered through the skin usingconventional transdermal patch or other transdermal delivery system,wherein the conjugate is contained within a laminated structure thatserves as a drug delivery device to be affixed to the skin. In such astructure, the conjugate is contained in a layer, or “reservoir,”underlying an upper backing layer. The laminated structure can contain asingle reservoir, or it can contain multiple reservoirs.

The conjugate can also be formulated into a suppository for rectaladministration. With respect to suppositories, the conjugate is mixedwith a suppository base material which is (e.g., an excipient thatremains solid at room temperature but softens, melts or dissolves atbody temperature) such as coca butter (theobroma oil), polyethyleneglycols, glycerinated gelatin, fatty acids, and combinations thereof.Suppositories can be prepared by, for example, performing the followingsteps (not necessarily in the order presented): melting the suppositorybase material to form a melt; incorporating the conjugate (either beforeor after melting of the suppository base material); pouring the meltinto a mold; cooling the melt (e.g., placing the melt-containing mold ina room temperature environment) to thereby form suppositories; andremoving the suppositories from the mold.

The invention also provides a method for administering a conjugate asprovided herein to a patient suffering from a condition that isresponsive to treatment with the conjugate. The method comprisesadministering, generally orally, a therapeutically effective amount ofthe conjugate (preferably provided as part of a pharmaceuticalpreparation). Other modes of administration are also contemplated, suchas pulmonary, nasal, buccal, rectal, sublingual, transdermal, andparenteral. As used herein, the term “parenteral” includes subcutaneous,intravenous, intra-arterial, intraperitoneal, intracardiac, intrathecal,and intramuscular injection, as well as infusion injections.

In instances where parenteral administration is utilized, it may benecessary to employ somewhat bigger oligomers than those describedpreviously, with molecular weights ranging from about 500 to 30K Daltons(e.g., having molecular weights of about 500, 1000, 2000, 2500, 3000,5000, 7500, 10000, 15000, 20000, 25000, 30000 or even more).

The method of administering may be used to treat any condition that canbe remedied or prevented by administration of the particular conjugate.Those of ordinary skill in the art appreciate which conditions aspecific conjugate can effectively treat. The actual dose to beadministered will vary depend upon the age, weight, and generalcondition of the subject as well as the severity of the condition beingtreated, the judgment of the health care professional, and conjugatebeing administered. Therapeutically effective amounts are known to thoseskilled in the art and/or are described in the pertinent reference textsand literature. Generally, a therapeutically effective amount will rangefrom about 0.001 mg to 1000 mg, preferably in doses from 0.01 mg/day to750 mg/day, and more preferably in doses from 0.10 mg/day to 500 mg/day.

The unit dosage of any given conjugate (again, preferably provided aspart of a pharmaceutical preparation) can be administered in a varietyof dosing schedules depending on the judgment of the clinician, needs ofthe patient, and so forth. The specific dosing schedule will be known bythose of ordinary skill in the art or can be determined experimentallyusing routine methods. Exemplary dosing schedules include, withoutlimitation, administration five times a day, four times a day, threetimes a day, twice daily, once daily, three times weekly, twice weekly,once weekly, twice monthly, once monthly, and any combination thereof.Once the clinical endpoint has been achieved, dosing of the compositionis halted.

All articles, books, patents, patent publications and other publicationsreferenced herein are incorporated by reference in their entireties. Inthe event of an inconsistency between the teachings of thisspecification and the art incorporated by reference, the meaning of theteachings in this specification shall prevail.

EXPERIMENTAL

It is to be understood that while the invention has been described inconjunction with certain preferred and specific embodiments, theforegoing description as well as the examples that follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

All non-PEG chemical reagents referred to in the appended examples arecommercially available unless otherwise indicated. The preparation ofPEG-mers is described in, for example, U.S. Patent ApplicationPublication No. 2005/0136031.

All ¹H NMR (nuclear magnetic resonance) data was generated by a 300 MHzNMR spectrometer manufactured by Bruker. A list of certain compounds aswell as the source of the compounds is provided below.

Example 1

The syntheses of PEG conjugates of BW373U86 and its analogs.

N,N-Diethyl-4-formylbenzamide (1)

4-Carboxybenzaldehyde (1.07 g, 7.13 mmol) was added into SOCl₂ (5 ml).The mixture was refluxed for 6 hours until the solid was totallydissolved in solution. Then SOCl₂ was evaporated under reduced pressure.Toluene (10 ml) was added to the residue and then removed under reducedpressure. The resulting residue was dissolved in anhydrous DCM (10 ml).Et₂NH (20 mmol, 2.07 ml) was added dropwise. The solution was stirred atroom temperature overnight. The solvent was removed under reducedpressure and the resulting residue was subjected to flash chromatography(EtOAc/Hexanes=30%˜50%) to give compound (1) (1.32 g, 6.44 mmol, yield90%). ¹H NMR (CDCl₃) δ 10.06 (s, 1H), 7.95 (d, 2H), 7.55 (d, 2H), 3.58(quart, 2H), 3.23 (quart, 2H), 1.28 (t, 3H), 1.13 (t, 3H).

3-Bromophenyl tert-butyldimethylsilyl ether (2)

3-Bromophenol (6 mmol, 1.04 g), imidazole (10 mmol, 0.68 g) and TBDMSCl(6.6 mmol, 0.99 g) were dissolved in DCM (20 ml). The solution wasallowed to stir at room temperature overnight. The solid generatedduring the reaction was filtered off and the solvent removed underreduced pressure. The resulting residue was subjected to flashchromatography (EtOAc/Hexanes=3%˜15%) giving compound 2 (1.56 g, 5.44mmol, yield 91%). ¹H NMR (CDCl₃): δ 7.11-7.08 (m, 2H), 7.03-7.02 (m,1H), 6.80-6.77 (m, 1H), 0.99 (s, 9H), 0.31 (s, 6H).

N,N-Diethyl-4-[hydroxy-(3-O-TBDMS-phenyl)-methyl]benzamide (3)

Compound 2 (1.55 g, 5.42 mmol) was dissolved in anhydrous THF (30 ml).At −78° C., n-BuLi solution (3.44 ml, 5.5 mmol, 1.6 M in Hexanessolution) was added dropwise. After 30 minutes, a solution of compound 1(1.13 g, 5.50 mmol) in THF (8 ml) was added dropwise with stirring. Thereaction solution was allowed to warm up to room temperature in a periodof 3 hrs. Then a saturated NH₄Cl solution (5 ml) was added to quench thereaction. The solution was extracted with DCM (20 ml×3). The organicphases were combined, dried over Na₂SO₄, filtered, and the solventremoved under reduced pressure. The resulting residue was subjected toflash chromatography (EtOAc/Hexanes=12%˜60%) to give compound 3 (1.23 g,2.97 mmol, yield 54%). ¹H NMR (CDCl₃): δ 7.33 (d, 2H), 7.23 (d, 2H),7.15-7.12 (m, 1H), 6.94-6.91 (m, 1H), 6.84-6.83 (m, 1H), 6.73-6.70 (m,1H), 5.69 (d, 1H), 3.73 (d, 1H), 3.48 (m, 2H), 3.22 (m, 2H), 1.19 (m,3H), 1.08 (m, 3H), 0.97 (s, 9H), 0.15 (s, 6H).

(±)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamid[(±)-4a]

Compound 3 (800 mg, 1.94 mmol) was dissolved in DCM (20 ml). SOCl₂ (3mmol, 0.22 ml) was added to the solution at room temperature andcontinued to stir at room temperature for 1 hour once addition wascomplete. After 1 hour, the solvent was removed under reduced pressureand toluene (10 ml) was added. The toluene was subsequently removedunder reduced pressure and the resulting residue, without furtherpurification, was mixed with (±)-trans-1-allyl-2,5-dimethylpiperazine(3.0 mmol, 459 mg), K₂CO₃ (6 mmol, 828 mg), NaI (3 mmol, 450 mg) inanhydrous acetonitrile (20 ml). The reaction solution was stirred andrefluxed overnight. The solid was filtered off and the solvent wasremoved under reduced pressure. The resulting residue was subjected toflash chromatography (EtOAc/Hexanes=20%˜80%) giving (±)-4a (450 mg, 0.82mmol, yield 42%) as the first spot to elute and (±)-4b (460 mg, 0.84mmol, yield 43%) as the second spot to elute.

Compound (±)-4a: ¹H NMR (CDCl₃): δ 7.47 (d, 2H), 7.30 (d, 2H), 7.20-7.15(m, 1H), 6.80-6.74 (m, 2H), 6.61 (s, 1H), 5.89-5.80 (m, 1H), 5.20-5.11(m, 3H), 3.54-3.44 (m, 2H), 3.38-3.32 (m, 3H), 2.88-2.77 (m, 2H),2.60-2.55 (m, 2H), 2.55-2.42 (m, 1H), 2.16-2.09 (m, 1H), 1.89-1.86 (m,1H), 1.26-1.12 (m, 6H), 1.20 (d, 3H), 0.99 (d, 3H), 0.96 (s, 9H), 0.16(s, 6H).

Compound (±)-4b: ¹H NMR (CDCl₃): δ 7.34 (d, 2H), 7.26 (d, 2H), 7.11 (t,1H), 7.01 (s, 1H), 6.91-6.89 (m, 1H), 6.72-6.69 (m, 1H), 5.87-5.81 (m,1H), 5.20-5.12 (m, 3H), 3.54-3.44 (m, 2H), 3.38-3.32 (m, 3H), 2.89-2.78(m, 2H), 2.69-2.49 (m, 3H), 2.16-2.09 (m, 1H), 1.90-1.89 (m, 1H),1.26-1.17 (m, 6H), 1.19 (d, 3H), 0.99 (d, 3H), 0.96 (s, 9H), 0.16 (s,6H).

(±)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-hydroxbenzyl]-N,N-diethylbenzamide[(±)-5)]

Compound (±)-4a (360 mg, 0.66 mmol) was dissolved in THF (15 ml) andBu₄NF (1.0 mmol, 1.0 ml, 1.0 M solution in THF) was added to thesolution with stirring. The reaction solution was stirred at roomtemperature for 1.5 hours. The solvent was removed under reducedpressure and the resulting residue was subjected to flash chromatography(MeOH/DCM=2%˜5%) to give compound (±)-5 (198 mg, 0.46 mmol, yield 70%).¹H NMR (CDCl₃): δ 7.45 (d, 2H), 7.39 (d, 2H), 7.10-7.05 (m, 1H),6.60-6.55 (m, 3H), 5.95-5.84 (m, 1H), 5.25-5.17 (m, 3H), 3.55-3.31 (m,5H), 2.94-2.85 (m, 2H), 2.66-2.50 (m, 3H), 2.18 (t, 1H), 1.95 (t, 1H),1.24-0.93 (m, 7H), 1.17 (d, 3H), 1.01 (d, 3H).

(±)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-O-methoxy(triethyleneglycol)benzyl]-N,N-diethylbenzamid [(±)-6]

Compound (±)-5 (100 mg, 0.23 mmol) was dissolved in anhydrous DMF (5 ml)and NaH (20 mg, 60% in mineral oil, 0.5 mmol) was added to the solutionat room temperature with stirring. The solution continued to stir atroom temperature for 10 minutes at which point, methoxy tri(ethyleneglycol) bromide (100 mg, 0.44 mmol) was added. The resulting reactionsolution was stirred at room temperature for 2 hours. Sat. NH₄Clsolution (1 ml) was added to the solution and the solvent removed underreduced pressure. The resulting residue was subjected to flashchromatography (MeOH/DCM=2%˜6%) to give compound (±)-6 (102 mg, 0.18mmol, yield 76%). ¹H NMR (CDCl₃): δ 7.45 (d, 2H), 7.28 (d, 2H), 7.21 (t,1H), 6.82-6.73 (m, 3H), 5.86-5.83 (m, 1H), 5.19-5.11 (m, 3H), 4.06 (t,2H), 3.84 (t, 2H), 3.73-3.63 (m, 6H), 3.55-3.52 (m, 4H), 3.36 (s, 3H),3.35-3.31 (m, 3H), 2.80-2.62 (m, 2H), 2.60-2.56 (m, 2H), 2.50-2.45 (m,1H), 2.12 (t, 1H), 1.89 (t, 1H), 1.22-1.02 (m, 6H), 1.18 (d, 3H), 1.00(d, 3H). LC/MS 582 [M+H]⁺, 604 [M+Na]⁺.

(±)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-O-methoxy(heptaethyleneglycol)benzyl]-N,N-diethylbenzamid [(±)-7]

Compound (±)-5 (85 mg, 0.20 mmol) was dissolved in anhydrous DMF (5 ml)and NaH (16 mg, 60% in mineral oil, 0.4 mmol) was added to the solutionat room temperature with stirring. The solution continued to stir atroom temperature for 10 minutes at which point, methoxy hepta(ethyleneglycol) bromide (121 mg, 0.30 mmol) was added. The resulting reactionsolution was stirred at room temperature for 2 hours. Sat. NH₄Clsolution (1 ml) was added to the solution and the solvent removed underreduced pressure. The resulting residue was subjected to flashchromatography (MeOH/DCM=2%˜6%) to give compound (±)-7 (130 mg, 0.17mmol, yield 86%). ¹H NMR (CDCl₃): δ 7.42 (d, 2H), 7.24 (d, 2H), 7.19 (t,1H), 6.80-6.71 (m, 3H), 5.85-5.80 (m, 1H), 5.19-5.11 (m, 3H), 4.05 (t,2H), 3.81 (t, 2H), 3.69-3.59 (m, 22H), 3.52-3.49 (m, 4H), 3.34 (s, 3H),3.35-3.32 (m, 3H), 2.82-2.75 (m, 2H), 2.61-2.53 (m, 3H), 2.10 (t, 1H),1.90 (t, 1H), 1.22-1.01 (m, 6H), 1.14 (d, 3H), 0.99 (d, 3H). LC/MS 758[M+H]⁺, 780 [M+Na]⁺.

(+)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamid[(+)-4a]

Compound 3 (1.10 g, 2.66 mmol) was dissolved in DCM (20 ml) and SOCl₂ (4mmol, 0.3 ml) was added to the solution at room temperature andcontinued to stir at room temperature for 1 hour once addition wascomplete. After 1 hour, the solvent was removed under reduced pressureand toluene (10 ml) was added. The toluene was subsequently removedunder reduced pressure and the resulting residue, without furtherpurification, was mixed with (−)-(2R,5S)-1-allyl-2,5-dimethylpiperazine(2.8 mmol, 428 mg), K₂CO₃ (6 mmol, 828 mg), NaI (3 mmol, 450 mg) inanhydrous acetonitrile (25 ml). The reaction solution was stirred andrefluxed overnight. The solid was filtered off and the solvent removedunder reduced pressure. The resulting residue was subjected to flashchromatography (EtOAc/Hexanes=20%˜80%) giving (+)-4a (390 mg, 0.73 mmol,yield 27%) as the first spot to elute and (+)-4b (440 mg, 0.84 mmol,yield 31%) as the second spot to elute.

Compound (+)-4a: ¹H NMR (CDCl₃): δ 7.47 (d, 2H), 7.30 (d, 2H), 7.20-7.15(m, 1H), 6.80-6.74 (m, 2H), 6.61 (s, 1H), 5.89-5.80 (m, 1H), 5.20-5.11(m, 3H), 3.54-3.44 (m. 2H), 3.38-3.32 (m, 3H), 2.88-2.77 (m, 2H),2.60-2.55 (m, 2H), 2.55-2.42 (m, 1H), 2.16-2.09 (m, 1H), 1.89-1.86 (m,1H), 1.26-1.12 (m, 6H), 1.20 (d, 3H), 0.99 (d, 3H), 0.96 (s, 9H), 0.16(s, 6H).

Compound (+)-4b: ¹H NMR (CDCl₃): δ 7.34 (d, 2H), 7.26 (d, 2H), 7.11 (t,1H), 7.01 (s, 1H), 6.91-6.89 (m, 1H), 6.72-6.69 (m, 1H), 5.87-5.81 (m,1H), 5.20-5.12 (m, 3H), 3.54-3.44 (m, 2H), 3.38-3.32 (m, 3H), 2.89-2.78(m, 2H), 2.69-2.49 (m, 3H), 2.16-2.09 (m, 1H), 1.90-1.89 (m, 1H),1.26-1.17 (m, 6H), 1.19 (d, 3H), 0.99 (d, 3H), 0.96 (s, 9H), 0.16 (s,6H).

(+)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-hydroxbenzyl]-N,N-diethylbenzamide[(+)-5)]

Compound (+)-4a (390 mg, 0.73 mmol) was dissolved in THF (20 ml) andBu₄NF (1.1 mmol, 1.1 ml, 1.0 M solution in THF) was added to thesolution with stirring. The reaction solution was allowed to stir atroom temperature for 1 hour. The solvent was removed under reducedpressure. The resulting residue was subjected to flash chromatography(MeOH/DCM=2%˜5%) to give compound (+)-5 (310 mg, 0.71 mmol, yield 98%).¹H NMR (CDCl₃): δ 7.45 (d, 2H), 7.39 (d, 2H), 7.10-7.05 (m, 1H),6.60-6.55 (m, 3H), 5.95-5.84 (m, 1H), 5.25-5.17 (m, 3H), 3.55-3.31 (m,5H), 2.94-2.85 (m, 2H), 2.66-2.50 (m, 3H), 2.18 (t, 1H), 1.95 (t, 1H),1.24-0.93 (m, 7H), 1.17 (d, 3H), 1.01 (d, 3H).

(+)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-O-methoxy(triethyleneglycol)benzyl]-N,N-diethylbenzamid [(+)-6]

Compound (+)-5 (110 mg, 0.25 mmol) was dissolved in anhydrous DMF (5 ml)and NaH (20 mg, 60% in mineral oil, 0.5 mmol) was added to the solutionat room temperature with stirring. The solution continued to stir atroom temperature for 10 minutes at which point, methoxy tri(ethyleneglycol) bromide (100 mg, 0.44 mmol) was added. The resulting reactionsolution was stirred at room temperature for 2 hours. Sat. NH₄Clsolution (1 ml) was added to the solution and the solvent removed underreduced pressure. The resulting residue was subjected to flashchromatography (MeOH/DCM=2%˜6%) to give compound (+)-6 (120 mg, 0.21mmol, yield 83%). ¹H NMR (CDCl₃): δ 7.45 (d, 2H), 7.28 (d, 2H), 7.21 (t,1H), 6.82-6.73 (m, 3H), 5.86-5.83 (m, 1H), 5.19-5.11 (m, 3H), 4.06 (t,2H), 3.84 (t, 2H), 3.73-3.63 (m, 6H), 3.55-3.52 (m, 4H), 3.36 (s, 3H),3.35-3.31 (m, 3H), 2.80-2.62 (m, 2H), 2.60-2.56 (m, 2H), 2.50-2.45 (m,1H), 2.12 (t, 1H), 1.89 (t, 1H), 1.22-1.02 (m, 6H), 1.18 (d, 3H), 1.00(d, 3H). LC/MS 582 [M+H]⁺, 604 [M+Na]⁺.

(+)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-O-methoxy(heptaethyleneglycol)benzyl]-N,N-diethylbenzamid [(+)-7]

Compound (+)-5 (108 mg, 0.25 mmol) was dissolved in anhydrous DMF (5 ml)and NaH (20 mg, 60% in mineral oil, 0.5 mmol) was added to the solutionat room temperature with stirring. The solution continued to stir atroom temperature for 10 minutes, at which point, methoxy hepta(ethyleneglycol) bromide (121 mg, 0.30 mmol) was added. The resulting reactionsolution was stirred at room temperature for 2 hours. Sat. NH₄Clsolution (1 ml) was added to the solution and the solvent removed underreduced pressure. The resulting residue was subjected to flashchromatography (MeOH/DCM=2%˜6%) to give compound (+)-7 (145 mg, 0.19mmol, yield 77%). ¹H NMR (CDCl₃): δ 7.42 (d, 2H), 7.24 (d, 2H), 7.19 (t,1H), 6.80-6.71 (m, 3H), 5.85-5.80 (m, 1H), 5.19-5.11 (m, 3H), 4.05 (t,2H), 3.81 (t, 2H), 3.69-3.59 (m, 22H), 3.52-3.49 (m, 4H), 3.34 (s, 3H),3.35-3.32 (m, 3H), 2.82-2.75 (m, 2H), 2.61-2.53 (m, 3H), 2.10 (t, 1H),1.90 (t, 1H), 1.22-1.01 (m, 6H), 1.14 (d, 3H), 0.99 (d, 3H). LC/MS 758[M+H]⁺, 780 [M+Na]⁺.

4-[(4-Allyl-1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamide (8)

Compound 3 (480 mg, 1.16 mmol) was dissolved in DCM (20 ml) and SOCl₂(2.66 mmol, 0.20 ml) was added to the solution at room temperature withstirring. The solution continued to stir at room temperature for 3hours. Then the solvent was removed under reduced pressure and toluene(10 ml) was added to the resulting residue. The toluene was subsequentlyremoved under reduced pressure and the resulting residue, withoutfurther purification, was mixed with 1-allylpiperazine (1.5 mmol, 189mg), K₂CO₃ (3 mmol, 414 mg), NaI (1.5 mmol, 225 mg) in anhydrousacetonitrile (20 ml). The reaction solution was stirred and refluxedovernight. The solid was filtered off and the solvent removed underreduced pressure. The resulting residue was subjected to flashchromatography (MeOH/DCM=2%˜7%) to give compound 8 (560 mg, 1.07 mmol,yield 93%). ¹H NMR (CDCl₃): δ 7.43 (d, 2H), 7.27 (d, 2H), 7.10 (t, 1H),6.96-6.91 (m, 2H), 6.67-6.64 (m, 1H), 5.89-5.80 (m, 1H), 5.19-5.10 (m,3H), 4.17 (s, 1H), 3.54-3.44 (m, 2H), 3.38-3.34 (m, 2H), 2.99 (d, 2H),2.60-2.40 (m, 7H), 1.26-0.99 (m, 6H), 0.96 (s, 9H), 0.15 (s, 6H).

4-[(4-Allyl-1-piperazinyl)-3-hydroxbenzyl]-N,N-diethylbenzamid (9)

Compound 8 (560 mg, 1.07 mmol) was dissolved in THF (20 ml) and Bu₄NF(1.5 mmol, 1.5 ml, 1.0 M solution in THF) was added to the solution withstirring. The reaction solution continued to stir at room temperaturefor 2.5 hours. The solvent was removed under reduced pressure and theresulting residue was subjected to flash chromatography(MeOH/DCM=2%˜10%) to give compound 9 (420 mg, 1.03 mmol, yield 96%). ¹HNMR (CDCl₃): δ 7.42 (d, 2H), 7.30 (d, 2H), 7.13 (t, 1H), 6.96-6.86 (m,2H), 6.67-6.64 (m, 1H), 5.92-5.83 (m, 2H), 5.23-5.15 (m, 2H), 4.16 (s,1H), 3.55-3.45 (m, 2H), 3.36-3.22 (m, 2H), 3.04 (d, 2H), 2.60-2.32 (m,7H), 1.32-1.03 (m, 6H).

4-[(4-Allyl-1-piperazinyl)-3-O-methoxy(triethyleneglycol)benzy]-N,N-diethylbenzamid(10)

Compound 9 (84 mg, 0.21 mmol) was dissolved in anhydrous DMF (5 ml) andNaH (16 mg, 60% in mineral oil, 0.4 mmol) was added to the solution atroom temperature with stirring. The reaction solution continued to stirat room temperature for 10 minutes at which point, methoxy tri(ethyleneglycol) mesylate (96.8 mg, 0.40 mmol) was added. The reaction solutionwas stirred at room temperature for 24 hours. Sat. NH₄Cl solution (1 ml)was added to the solution. The solvent was removed under reducedpressure and the resulting residue was subjected to flash chromatography(MeOH/DCM=2%˜11%) giving compound 10 (95 mg, 0.17 mmol, yield 82%) ¹HNMR (CDCl₃): δ 7.42 (d, 2H), 7.27 (d, 2H), 7.16 (t, 1H), 6.99-6.93 (m,2H), 6.74-6.70 (m, 1H), 5.86-5.81 (m, 1H), 5.20-5.11 (m, 2H), 4.18 (s,1H), 4.16 (t, 2H), 3.84 (t, 2H), 3.73-3.63 (m, 6H), 3.55-3.50 (m, 3H),3.37 (s, 3H), 3.25-3.20 (m, 1H), 3.01 (d, 2H), 2.62-2.30 (m, 8H),1.19-1.00 (m, 6H). LC/MS 554 [M+H]⁺, 576 [M+Na]⁺.

4-[(4-Allyl-1-piperazinyl)-3-O-methoxy(heptaethyleneglycol)benzyl]-N,N-diethylbenzamide (11)

Compound 9 (190 mg, 0.47 mmol) was dissolved in anhydrous DMF (5 ml) andNaH (40 mg, 60% in mineral oil, 1.0 mmol) was added to the solution atroom temperature with stirring. The reaction solution continued to stirat room temperature for 10 minutes at which point, methoxyhepta(ethylene glycol) bromide (242 mg, 0.60 mmol) was added. Thereaction solution was stirred at room temperature for 3.5 hours. Sat.NH₄Cl solution (2 ml) was added to the solution. The solvent was removedunder reduced pressure and the resulting residue was subjected to flashchromatography (MeOH/DCM=2%˜10%) giving compound 11 (255 mg, 0.35 mmol,yield 74%). ¹H NMR (CDCl₃): δ 7.41 (d, 2H), 7.26 (d, 2H), 7.15 (t, 1H),6.98-6.95 (m, 2H), 6.73-6.70 (m, 1H), 5.86-5.80 (m, 1H), 5.20-5.11 (m,2H), 4.18 (s, 1H), 4.08 (t, 2H), 3.83 (t, 2H), 3.71-3.62 (m, 22H),3.53-3.51 (m, 3H), 3.36 (s, 3H), 3.20-3.15 (m, 1H), 3.02 (d, 2H),2.66-2.30 (m, 8H), 1.19-1.05 (m, 6H). LC/MS 730 [M+H]⁺, 752 [M+Na]⁺.

4-[(1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamid (12)

Compound 3 (190 mg, 0.46 mmol) was dissolved in DCM (10 ml) and SOCl₂(1.33 mmol, 0.10 ml) was added to the solution at room temperature withstirring. The solution continued to stir at room temperature for 3hours. Then the solvent was removed under reduced pressure and toluene(10 ml) was added to the resulting residue. The toluene was subsequentlyremoved under reduced pressure and the resulting residue, withoutfurther purification, was mixed with piperazine (1.38 mmol, 119 mg),K₂CO₃ (2.3 mmol, 317 mg) in anhydrous acetonitrile (20 ml). The reactionsolution was stirred and refluxed for 2 hours. The solvent was removedunder reduced pressure. The residue was dissolved in EtOAc (20 ml) whichwas washed with H₂O (20 ml×3). The organic phases were combined, driedover Na₂SO₄, filtered and the solvent removed under reduced pressure togive compound 12 (220 mg, 0.45 mmol, yield 98%). ¹H NMR (CDCl₃): δ 7.43(d, 2H), 7.29 (d, 2H), 7.12 (t, 1H), 6.97-6.93 (m, 2H), 6.59-6.65 (m,1H), 4.17 (s, 1H), 3.54-3.44 (m, 2H), 3.38-3.24 (m, 2H), 2.89-2.86 (d,4H), 2.40-2.30 (m, 4H), 1.86-1.66 (m, 1H), 1.26-1.10 (m, 6H), 0.96 (s,9H), 0.15 (s, 6H).

4-[(4-Benzyl-1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamid (13)

Compound 12 (220 mg, 0.46 mmol) was mixed with benzyl bromide (0.50mmol, 0.06 ml), K₂CO₃ (1.0 mmol, 138 mg) in anhydrous acetonitrile (10ml). The reaction solution was stirred at 50° C. for 30 minutes. Thesolid was filtered off and the solvent was removed under reducedpressure. The resulting residue was subjected to flash chromatography(EtOAc/Hexanes=20%˜70%) to give compound 13 (220 mg, 0.39 mmol, 84%). ¹HNMR (CDCl₃): δ 7.44 (d, 2H), 7.31-7.28 (m, 7H), 7.12 (t, 1H), 6.98-6.94(m, 2H), 6.70-6.67 (m, 1H), 4.20 (s, 1H), 3.58-3.48 (m, 4H), 3.30-3.20(m, 2H), 2.60-2.45 (m, 8H), 1.26-1.10 (m, 6H), 0.99 (s, 9H), 0.18 (s,6H).

4-[(4-Benzyl-1-piperazinyl)-3-hydroxbenzyl]-N,N-diethylbenzamid (14)

Compound 13 (220 mg, 0.39 mmol) was dissolved in THF (20 ml) and Bu₄NF(0.70 mmol, 0.7 ml, 1.0 M solution in THF) was added to the solutionwith stirring. The reaction solution continued to stir at roomtemperature for 1.5 hours and the solvent was removed under reducedpressure. The resulting residue was subjected to flash chromatography(MeOH/DCM=2%˜8%) to give compound 14 (160 mg, 0.35 mmol, yield 90%). ¹HNMR (CDCl₃): δ 7.38-7.23 (m, 9H), 7.03 (t, 1H), 6.87-6.82 (m, 2H),6.57-6.55 (m, 1H), 4.06 (s, 1H), 3.58-3.50 (m, 4H), 3.30-3.22 (m, 2H),2.55-2.25 (m, 8H), 1.28-1.10 (m, 6H).

4-[(4-Benzyl-1-piperazinyl)-3-O-methoxy(triethyleneglycol)benzyl]-N,N-diethylbenzamide(15)

Compound 14 (80 mg, 0.18 mmol) was dissolved in anhydrous DMF (10 ml)and NaH (16 mg, 60% in mineral oil, 0.4 mmol) was added to the solutionat room temperature. The solution continued to stir at room temperaturefor 10 minutes at which point, methoxy tri(ethylene glycol) mesylate(105 mg, 0.43 mmol) was added. The reaction solution was stirred at roomtemperature for 24 hours. Sat. NH₄Cl solution (1 ml) was added to thesolution. The solvent was removed under reduced pressure and theresulting residue was subjected to flash chromatography(MeOH/DCM=2%˜11%) to give a mixture of compound 15 with methoxytri(ethylene glycol) mesylate as the impurity. The mixture was dissolvedin DCM (2 ml). The solution was added to HCl in ethyl ether (1.0 M, 10ml). Upon addition, a white precipitate appeared and the cloudy solutionwas centrifuged (4000 rpm, 15 minutes). The clear solvent was removedand the residue in the tube was extracted with Sat. NaHCO₃ (5 ml) andDCM (5 ml×3). The organic phases were combined, dried over Na₂SO₄,filtered, and the solvent removed under reduced pressure to give thedesired compound 15 (75 mg, 0.12 mmol, yield 69%). ¹H NMR (CDCl₃): δ7.43 (d, 2H), 7.31-7.22 (m, 7H), 7.17 (t, 1H), 6.99-6.97 (m, 2H),6.75-6.72 (m, 1H), 4.20 (s, 1H), 4.10 (t, 2H), 3.87 (t, 2H), 3.75-3.66(m, 6H), 3.58-3.52 (m, 6H), 3.39 (s, 3H), 3.29-3.23 (m, 2H), 2.55-2.35(m, 8H), 1.28-1.10 (m, 6H). LC/MS 604 [M+H]⁺,626 [M+Na]⁺.

4-[(4-Benzyl-1-piperazinyl)-3-O-methoxy(heptaethyleneglycol)benzyl]-N,N-diethylbenzamid(16)

Compound 14 (65 mg, 0.15 mmol) was dissolved in anhydrous DMF (10 ml)and NaH (16 mg, 60% in mineral oil, 0.4 mmol) was added to the solutionat room temperature. The solution continued to stir at room temperaturefor 10 minutes at which point, methoxy hepta(ethylene glycol) bromide(80 mg, 0.20 mmol) was added. The reaction solution was stirred at roomtemperature for 24 hours. Sat. NH₄Cl solution (1 ml) was added into thesolution. The solvent was removed under reduced pressure and theresulting residue was subjected to flash chromatography(MeOH/DCM=2%˜11%) to give a mixture of compound 16 with methoxyhepta(ethylene glycol) bromide as the impurity. The mixture wasdissolved in DCM (2 ml). The solution was added to HCl in ethyl ether(1.0 M, 10 ml). Upon addition, a white precipitate appeared and thecloudy solution was centrifuged (4000 rpm, 15 minutes). The clearsolvent was removed and the residue in the tube was extracted with Sat.NaHCO₃ solution (5 ml) and DCM (5 ml×3). The organic phases werecombined, dried with Na₂SO₄, filtered, and the solvent removed underreduced pressure to give the desired compound 16 (72 mg, 0.09 mmol,yield 62%). ¹H NMR (CDCl₃): δ 7.42 (d, 2H), 7.30-7.22 (m, 7H), 7.13 (t,1H), 6.98-6.96 (m, 2H), 6.73-6.70 (m, 1H), 4.18 (s, 1H), 4.09 (t, 2H),3.85 (t, 2H), 3.82-3.62 (m, 22H), 3.56-3.51 (m, 6H), 3.38 (s, 3H),3.30-3.20 (m, 2H), 2.55-2.35 (m, 8H), 1.28-1.08 (m, 6H). LC/MS 780[M+H]⁺, 802 [M+Na]⁺.

n=3 as example (n may be different monomeric length)

(±)-4-[(αR)-α-((2S,5R)-2,5-dimethyl-1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamid[(±)-17]

Compound (±)-4a (0.5 mmol) is mixed with H₂O (6 ml), acetic acid (0.6ml), and Pd/C (10%, 100 mg). The solution is refluxed for 24 hours. ThePd/C powder is filtered off. The solvent is evaporated in vacuum. Theobtained compound (±)-17 is used in the next reaction without furtherpurification.

(±)-4-[(αR)-α-((2S,5R)-4-methoxy(triethyleneglycol)-2,5-dimethyl-1-piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamide[(±)-18]

Compound (±)-17 (0.4 mmol) is mixed with methoxy tri(ethylene glycol)bromide (0.50 mmol), K₂CO₃ (1.0 mmol) in anhydrous acetonitrile (10 ml).The reaction solution is stirred at 50° C. for 30 minutes. The solid isfiltered off and the solvent is evaporated under reduced pressure. Theresidue is subjected to flash chromatography to give compound (±)-18.

(±)-4-[(αR)-α-((2S,5R)-4-methoxy(triethyleneglycol)-2,5-dimethyl-1-piperazinyl)-3-hydroxybenzyl]-N,N-diethylbenzamide[(±)-19]

Compound (±)-18 (0.3 mmol) is mixed with dissolved in THF (10 ml) andTBAF (1.0 M in THF, 0.5 ml) is added to the reaction solution withstirring. The solution continued to stir at room temperature for 3hours. The solvent is removed under reduced pressure. The resultingresidue is subjected to flash chromatography to give compound (±)-19.

The synthesis procedure of (+)-17, (+)-18, and (+)-19 are similar to thesynthetic procedures of (±)-17, (±)-18, and (±)-19 as described above.The only difference is using (+)-4a as starting material instead of(±)-4a.

n=3 as example (n may be different monomeric length)

4-[4-methoxy(triethyleneglycol)-1-(piperazinyl)-3-O-TBDMS-benzyl]-N,N-diethylbenzamide(20)

Compound 12 (0.4 mmol) is mixed with methoxy tri(ethylene glycol)bromide (0.50 mmol), K₂CO₃ (1.0 mmol) in anhydrous acetonitrile (10 ml).The reaction solution is stirred at 50° C. for 30 minutes. The solid isfiltered off and the solvent is evaporated under reduced pressure. Theresulting residue is subjected to flash chromatography to give compound20.

4-[4-methoxy(triethyleneglycol)-1-(piperazinyl)-3-hydroxybenzyl]-N,N-diethylbenzamide(21)

Compound 20 (0.3 mmol) is mixed with dissolved in THF (10 ml) and TBAF(1.0 M in THF, 0.5 ml) is added to the reaction solution with stirring.The solution continued to stir at room temperature for 3 hours. Thesolvent is removed under reduced pressure. The resulting residue issubjected to flash chromatography to give compound 21.

Scheme 7: Synthesis of PEG-BW373U86 Conjugates via PhysiologicallyStable Linkages

Example 2 Receptor Binding

The binding constants for PEGylated compounds to human δ, κ, and μ,opioid receptors are determined using radioligand competition-bindingassays described previously. Test compounds are assayed for inhibitionof radioligand binding at final test-compound concentrations rangingbetween 0.01 μM and 100 μM in half-log increments. Briefly, cellmembrane preparations from cells expressing the specific receptor aremixed with a [³H]-labeled tracer (see table, below) and the testcompound or a known inhibitor of receptor-ligand binding. Followingincubation to allow receptor-ligand complex formation, the complexes arecollected by filtration, washed to remove radioligand that was notreceptor-bound, and the remaining radioactivity is determined by liquidscintillation counting. Specific radioligand binding is calculated foreach test compound concentration and IC₅₀ values are determined by anon-linear, least squares regression analysis using MathIQ™ (ID BusinessSolutions Ltd., UK). Reference standards are run with each assay toensure the validity of the results. Inhibition constants (K_(i)) werecalculated using the equation of Cheng and Prusoff using the observedIC₅₀ of the tested compound, the concentration of radioligand employedin the assay and the experimentally determined values for the K_(d) ofthe ligand. The Hill coefficient (n_(h)), defining the slope of thecompetitive binding curve, was calculated using MathIQ™.

Receptor Cell source Radioligand Opiate δ Chinese hamster ovary[³H]-naltrindole, 0.9 nM Opiate κ HEK-293 [³H]-diprenorphine, 0.6 nMOpiate μ Chinese hamster ovary [³H]-diprenorphine, 0.6 nMOpiate δ: source: Human recombinant (CHO cells)Ligand: 0.9 nM [³H] Naltrindolenon-specific: 10 μM NaloxoneK_(d): 0.49 nMB_(max): 8600 fmol/mg Proteinspecific binding 80%Opiate κ; source: Human recombinant (HEK-293 cells)Ligand: 0.6 nM [³H]DiprenorphineNon-specific: 10 μM NaloxoneK_(d): 0.4 nMB_(max): 1100 fmol/mg ProteinSpecific binding 90%Opiate μ; Source: Human recombinant CHO—K1 cellsLigand: 0.6 nM [³H] DiprenorphineVehicle: 1% DMSOIncubation Time/Temp: 60 minutes @ 25.0Incubation Buffer: 50 mM Tris-HCl, pH 7.4K_(d) ¹:0.41 nM *B_(MAX): 3.8 pmole/mg Protein *Non-Specific Ligand: 10 μl NaloxoneSpecific Binding: 90% *For all: Significance Criteria: >=50% of max stimulation or inhibitionQuantitation Method Radioligand Binding

TABLE 1 Molecule Opiate δ, Ki (nM) Fold change ±BW373U86 0.44, 0.36 1mPEG-3 ± BW373U86 ~415.4 ~98 mPEG-7 ± BW373U86 ~1330 ~298 mPEG-3 +BW373U86 491 137.23 mPEG-7 + BW373U86 863.5 242.7

TABLE 2 Opiate Receptor, delta (OP1, DOP) Compound IC₅₀, nM SEM Ki, nMSEM nH SEM mPEG₃-O-(+)BW373U86 723 55 255 20 0.95 0.19 (+) BW373U86 10.083 0.354 0.029 0.91 0.07 demethyl-BW373U86 7.09 1.05 2.5 0.368 1.100.17 mPEG₃-demethyl-BW373U86 6050 641 2130 226 1.01 0.16mPEG₇-demethyl-BW373U86 3470 820 1220 289 0.85 0.02N-benzyl-deallyl-demethyl- 1.33 0.131 0.47 0.046 0.99 0.04 BW373U86mPEG₃-N-benzyl-deallyl- 212 19 74.7 7 1.50 0.09 demethyl-BW373U86mPEG₇-N-benzyl-deallyl- 106 6 37.4 2 1.08 0.03 demethyl-BW373U86 (+/−)BW373U86 3.26 0.613 1.15 0.216 1.05 0.12 dihydrobromidemPEG3-N-(+/−)-BW373U86 764 176 269 62 0.95 0.04 mPEG7-N-(+/−)-BW373U862090 308 735 108 1.22 0.19

TABLE 3 Opiate Receptor, kappa (OP2, KOP) Compound IC₅₀, nM SEM Ki, nMSEM nH SEM mPEG₃-O-(+)BW373U86 ND ND ND ND ND ND (+) BW373U86  223 48  89.2 19 0.78 0.04 demethyl-BW373U86 1000 61 401 24 0.87 0.03mPEG₃-demethyl-BW373U86 ND ND ND ND ND ND mPEG₇-demethyl-BW373U86 ND NDND ND ND ND N-benzyl-deallyl-demethyl- 2370 274  946 110  0.95 0.09BW373U86 mPEG₃-N-benzyl-deallyl- ND ND ND ND ND ND demethyl-BW373U86mPEG₇-N-benzyl-deallyl- ND ND ND ND ND ND demethyl-BW373U86 (+/−)BW373U86 dihydrobromide  556 84 223 34 0.92 0.14 mPEG3-N-(+/−)-BW373U86ND ND ND ND ND ND mPEG7-N-(+/−)-BW373U86 ND ND ND ND ND ND

TABLE 4 Opiate (OP3, Receptor, μ MOP) IC₅₀, Ki, Compound nM SEM nM SEMnH SEM mPEG₃-O-(+)BW373U86 (+) BW373U86  309  35  126 14 0.83 0.05demethyl-BW373U86 11000 216 4450 88 1.02 0.02 mPEG₃-demethyl-BW373U86 NDND ND ND ND ND mPEG₇-demethyl-BW373U86 ND ND ND ND ND NDN-benzyl-deallyl-demethyl-  2750 206 1110 83 0.90 0.06 BW373U86mPEG₃-N-benzyl-deallyl- ND ND ND ND ND ND demethyl-BW373U86mPEG₇-N-benzyl-deallyl- ND ND ND ND ND ND demethyl-BW373U86 (+/−)BW373U86  659  18  268  7 0.92 0.04 dihydrobromidemPEG3-N-(+/−)-BW373U86  9370 243 3810 99 1.14 0.03mPEG7-N-(+/−)-BW373U86 ND ND ND ND ND ND

What is claimed is:
 1. A method of treatment comprising administering atherapeutically effective amount of a compound to a subject in need ofopioid receptor agonism, wherein the compound has a structure selectedfrom the group consisting of

wherein, in each structure, R³ is either H or CH₃, R⁵ is either H orCH₃, X is a spacer moiety, and POLY is a water-soluble, non-peptidicoligomer.
 2. The method of claim 1, wherein the water-soluble,non-peptidic oligomer is a poly(alkylene oxide).
 3. The method of claim2, wherein the poly(alkylene oxide) is a poly(ethylene oxide).
 4. Themethod of claim 1, wherein the water-soluble, non-peptidic oligomer hasbetween 1 and 30 monomers.
 5. The method of claim 4, wherein thewater-soluble, non-peptidic oligomer has between 1 and 10 monomers. 6.The method of claim 2, wherein the poly(alkylene oxide) includes analkoxy or hydroxy end-capping moiety.
 7. The method of claim 1, whereinthe water-soluble, non-peptidic oligomer is covalently attached via astable linkage.
 8. The method of claim 1, wherein the water-soluble,non-peptidic oligomer is covalently attached via a degradable linkage.9. The method of claim 1, wherein X is an oxygen.
 10. The method ofclaim 1, wherein X is an ester.
 11. The method of claim 1, wherein theopioid receptor is a delta opioid receptor.